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Graph trigonometric functions

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51009812
What is the period of \(f(x)=2\cos\left(\frac{\pi x}{1.5}\right)\)? a) \(1.5\) b) \(2\) c) \(3\) d) \(6\)

Hints

- Recall the period of the parent cosine function. - Identify the coefficient of \(x\) inside the cosine function. - Determine how that coefficient horizontally stretches or compresses the graph.

Solution

1. In the form \(a\cos(bx)\), the coefficient of \(x\) is \(b=\frac{\pi}{1.5}\). 2. The period is \(p=\frac{2\pi}{|b|}\). 3. Substitute: \(p=\frac{2\pi}{\pi/1.5}=3\).

Answer

c) \(3\)
52259912
The graph of \(h\) is obtained from \(f(x)=\cos(x)\) by applying these transformations in order: 1. Vertically stretch by a factor of \(3.5\). 2. Shift right \(\frac{\pi}{4}\) units. 3. Shift down \(2\) units. Write a rule for \(h\) and state its amplitude.

Hints

- Identify the parameter that controls vertical scale. - A shift right changes the input inside cosine. - A downward shift is represented by subtracting from the output. - Amplitude is the maximum distance from the midline.

Solution

1. The vertical stretch gives \(3.5\cos(x)\). 2. Shifting right \(\frac{\pi}{4}\) units replaces \(x\) with \(x-\frac{\pi}{4}\). 3. Shifting down \(2\) units gives \(h(x)=3.5\cos\left(x-\frac{\pi}{4}\right)-2\). 4. The amplitude is the absolute value of the outside coefficient, \(3.5\).

Answer

Function rule: \(h(x)=3.5\cos\left(x-\frac{\pi}{4}\right)-2\) Amplitude: \(3.5\)
52370812
Let \(h(x)=\sin(x-\pi)+4\). a) Describe the transformations from the graph of \(f(x)=\sin(x)\) to the graph of \(h\). b) Give the amplitude and equation of the midline.

Hints

- Identify the new constants inside and outside the sine expression. - A change inside the input affects horizontal position; an outside addition affects vertical position. - The midline is the horizontal line about which the graph oscillates. - Compare the height of the waves with the parent function.

Solution

1. The input \(x-\pi\) shifts the graph right by \(\pi\). 2. The outside term \(+4\) shifts the graph up \(4\) units. 3. The outside coefficient is \(1\), so the amplitude is \(1\). 4. The vertical shift gives the midline \(y=4\).

Answer

a) Shift right by \(\pi\) and up by \(4\). b) Amplitude: \(1\); midline: \(y=4\)
52371512
Starting with \(f(x)=\sin(x)\), write a function \(g\) for each set of transformations. a) Vertically stretch by a factor of \(5\), then shift up \(2\) units. b) Shift right by \(\frac{\pi}{2}\), then reflect across the x-axis. c) Vertically compress by a factor of \(0.4\), shift left \(3\) units, and shift down \(1\) unit.

Hints

- A vertical scale factor multiplies the function value. - A horizontal shift appears inside the function input with the opposite sign. - Reflection across the x-axis multiplies the function by \(-1\). - A vertical shift is added outside the sine expression.

Solution

1. For part a, multiply the function by \(5\) and add \(2\): \(g(x)=5\sin(x)+2\). 2. For part b, replace \(x\) with \(x-\frac{\pi}{2}\), then multiply by \(-1\): \(g(x)=-\sin\left(x-\frac{\pi}{2}\right)\). 3. For part c, multiply by \(0.4\), replace \(x\) with \(x+3\), and subtract \(1\): \(g(x)=0.4\sin(x+3)-1\).

Answer

a) \(g(x)=5\sin(x)+2\) b) \(g(x)=-\sin\left(x-\frac{\pi}{2}\right)\) c) \(g(x)=0.4\sin(x+3)-1\)
52372312
Find the amplitude \(A\) and period \(p\) of each function. a) \(f(x)=3\sin(0.5x)\) b) \(g(x)=-2\cos(\pi x)-5\) c) \(h(x)=\frac{1}{2}\sin\left(\frac{x}{4}\right)\)

Hints

- The coefficient outside sine or cosine determines the vertical stretch. - Amplitude is always nonnegative, even when the leading coefficient is negative. - The coefficient of \(x\) inside the function determines the horizontal stretch or compression. - Start with the parent period \(2\pi\).

Solution

1. For \(f\), the amplitude is \(|3|=3\). Since \(b=0.5\), the period is \(p=\frac{2\pi}{0.5}=4\pi\). 2. For \(g\), the amplitude is \(|-2|=2\). The vertical shift does not affect amplitude or period. Since \(b=\pi\), the period is \(p=\frac{2\pi}{\pi}=2\). 3. For \(h\), the amplitude is \(\left|\frac{1}{2}\right|=\frac{1}{2}\). Since \(b=\frac{1}{4}\), the period is \(p=\frac{2\pi}{1/4}=8\pi\).

Answer

a) \(A=3\); \(p=4\pi\) b) \(A=2\); \(p=2\) c) \(A=\frac{1}{2}\); \(p=8\pi\)
52373312
Describe the transformations from \(g(x)=\sin(x)\) to each function. a) \(f_1(x)=\sin(4x)\) b) \(f_2(x)=0.2\sin(x)-5\) c) \(f_3(x)=-3\sin(x)\)

Hints

- An outside coefficient changes the height of the waves. - A coefficient multiplying \(x\) changes the horizontal scale. - An outside addition or subtraction changes the vertical position. - A negative outside coefficient reflects the graph across the x-axis.

Solution

1. For \(f_1\), the coefficient \(4\) produces a horizontal compression by a factor of \(\frac{1}{4}\). The period changes from \(2\pi\) to \(\frac{\pi}{2}\). 2. For \(f_2\), the coefficient \(0.2\) produces a vertical compression, giving amplitude \(0.2\), and the term \(-5\) shifts the graph down \(5\) units. 3. For \(f_3\), the negative sign reflects the graph across the x-axis, and the factor \(3\) vertically stretches it to amplitude \(3\).

Answer

a) Horizontal compression by a factor of \(\frac{1}{4}\); period \(\frac{\pi}{2}\) b) Vertical compression to amplitude \(0.2\), then a shift down \(5\) units c) Reflection across the x-axis and vertical stretch to amplitude \(3\)
52373512
Determine whether each statement is true. Briefly justify your answer and correct any false statement. a) The function \(f(x)=0.5\sin(2x)\) has period \(\pi\). b) The graph of \(g(x)=4\sin(x)\) is obtained by vertically stretching the graph of the parent sine function by a factor of \(4\). c) The function \(h(x)=\sin(4x)\) has a greater period than \(k(x)=\sin(2x)\).

Hints

- Use the coefficient of \(x\) to calculate the period. - Identify which parameter in \(y=a\sin(bx)\) controls vertical stretching. - Consider how a larger value of \(b\) changes the speed of oscillation.

Solution

1. For \(f\), \(p=\frac{2\pi}{2}=\pi\), so statement a is true. 2. The coefficient \(4\) in \(g(x)=4\sin(x)\) produces a vertical stretch by a factor of \(4\), so statement b is true. 3. For \(h\), \(p_h=\frac{2\pi}{4}=\frac{\pi}{2}\). For \(k\), \(p_k=\frac{2\pi}{2}=\pi\). Since \(\frac{\pi}{2}<\pi\), statement c is false; \(h\) has the smaller period.

Answer

a) True. b) True. c) False. The period of \(h\) is \(\frac{\pi}{2}\), which is less than the period \(\pi\) of \(k\).
52857912
Let \(f(x)=1.5\sin(x)\). a) Find the range of \(f\). b) Find all zeros of \(f\) in the interval \([0, 2\pi]\).

Hints

- Recall the minimum and maximum values of the parent sine function. - Consider how an outside coefficient changes the amplitude. - Recall where the sine graph crosses the x-axis. - A vertical stretch does not change the x-intercepts.

Solution

1. The parent sine function has range \([-1, 1]\). Multiplying by \(1.5\) gives the range \([-1.5, 1.5]\). 2. The equation \(1.5\sin(x)=0\) is equivalent to \(\sin(x)=0\). 3. In \([0, 2\pi]\), sine is zero at \(x=0\), \(x=\pi\), and \(x=2\pi\).

Answer

a) \([-1.5, 1.5]\) b) \(x=0, \pi, 2\pi\)
52858012
Consider \(g(x)=\cos(x)\). a) Find all zeros of \(g\) on \([-\pi, \pi]\). b) Give the range of \(h(x)=\cos(x)-1\).

Hints

- Recall where the cosine graph crosses the x-axis. - Subtracting a constant shifts a graph vertically. - Apply the vertical shift to both endpoints of the original range.

Solution

1. Cosine is zero where the unit-circle x-coordinate is \(0\). In \([-\pi, \pi]\), this occurs at \(x=-\frac{\pi}{2}\) and \(x=\frac{\pi}{2}\). 2. The range of \(\cos(x)\) is \([-1, 1]\). Subtracting \(1\) shifts every output down by \(1\), so the range of \(h\) is \([-2, 0]\).

Answer

a) \(x=-\frac{\pi}{2}\) and \(x=\frac{\pi}{2}\) b) \([-2, 0]\)
52858112
Consider \(f(x)=\cos(x)\). a) State the greatest and least possible function values. b) Give the range of \(f\). c) Find all \(x \in [0, 2\pi]\) where \(f\) attains its minimum value.

Hints

- Cosine is the x-coordinate on the unit circle. - Use the highest and lowest x-coordinates to identify the range. - Locate the minimum point of one cosine period.

Solution

1. The greatest value of cosine is \(1\), and the least value is \(-1\). 2. Therefore, the range is \([-1, 1]\). 3. On \([0, 2\pi]\), cosine equals \(-1\) only at \(x=\pi\).

Answer

a) Maximum: \(1\); minimum: \(-1\) b) \([-1, 1]\) c) \(x=\pi\)
52858712
For \(f(x)=\sin(x)\), find all \(x\) in \([-2\pi, 2\pi]\) where the function has a zero. Also find all \(x\) in this interval for which \(\sin(x)=-1\).

Hints

- Recall where the sine graph crosses the x-axis. - Use the period of sine to locate repeated minima. - Use the repeating sine pattern over the interval to identify all relevant points. - Check the multiples of \(\pi\) and odd multiples of \(\frac{\pi}{2}\) within the endpoints.

Solution

1. The zeros of sine occur at \(x=k\pi\), where \(k \in \mathbb{Z}\). In \([-2\pi, 2\pi]\), these are \(-2\pi\), \(-\pi\), \(0\), \(\pi\), and \(2\pi\). 2. Sine equals \(-1\) at \(x=\frac{3\pi}{2}+2k\pi\), where \(k \in \mathbb{Z}\). 3. The values in the given interval are \(x=-\frac{\pi}{2}\) and \(x=\frac{3\pi}{2}\).

Answer

Zeros: \(x \in \{-2\pi, -\pi, 0, \pi, 2\pi\}\) Values where \(\sin(x)=-1\): \(x \in \left\{-\frac{\pi}{2}, \frac{3\pi}{2}\right\}\)
52858812
Consider \(f(x)=\sin(x)\) on \([0, 3\pi]\). a) At which values of \(x\) does the function attain its maximum value? b) At which values of \(x\) does the function attain its minimum value?

Hints

- What are the highest and lowest values reached by the sine graph? - The sine function has period \(2\pi\). - Identify the maximum and minimum locations in one period, then repeat them as needed.

Solution

1. The maximum value of sine is \(1\), attained at \(x=\frac{\pi}{2}+2k\pi\). In \([0, 3\pi]\), this gives \(x=\frac{\pi}{2}\) and \(x=\frac{5\pi}{2}\). 2. The minimum value of sine is \(-1\), attained at \(x=\frac{3\pi}{2}+2k\pi\). In \([0, 3\pi]\), the only such value is \(x=\frac{3\pi}{2}\).

Answer

a) \(x=\frac{\pi}{2}\) and \(x=\frac{5\pi}{2}\) b) \(x=\frac{3\pi}{2}\)
52862712
For \(f(x)=2.5\sin(0.5x)\), determine the amplitude, period, range, and symmetry of the graph.

Hints

- Identify the coefficient that controls the vertical stretch. - Relate the coefficient of \(x\) to the period. - Start with the minimum and maximum values of sine. - Recall the odd-function symmetry of the parent sine function.

Solution

1. The amplitude is \(|2.5|=2.5\). 2. The period is \(p=\frac{2\pi}{0.5}=4\pi\). 3. Since sine ranges from \(-1\) to \(1\), the range of \(f\) is \([-2.5, 2.5]\). 4. Because sine is odd, \(f(-x)=2.5\sin(-0.5x)=-f(x)\). Therefore, the graph has rotational symmetry about the origin.

Answer

Amplitude: \(2.5\); period: \(4\pi\); range: \([-2.5, 2.5]\); symmetry: rotational symmetry about the origin
52863512
The graph of \(f(x)=\cos(x)\) is vertically stretched by a factor of \(2.5\) and horizontally scaled by a factor of \(0.8\). Write the resulting function \(g(x)\).

Hints

- The outside coefficient controls vertical scaling. - A horizontal scale factor changes the input by its reciprocal. - Compare the result with the form \(a\cos(bx)\).

Solution

1. The vertical stretch gives an outside coefficient of \(2.5\). 2. A horizontal scale factor of \(0.8\) replaces \(x\) with \(\frac{x}{0.8}=1.25x\). 3. Therefore, \(g(x)=2.5\cos(1.25x)\).

Answer

\(g(x)=2.5\cos(1.25x)\)
53352912
The graph shows a sine function of the form \(f(x)=a\sin(bx)\). The x-axis is labeled in multiples of \(\pi\). Determine the function.
Figure for problem 533529

Hints

- Read the amplitude from the maximum and minimum values. - Find the shortest horizontal interval over which the pattern repeats. - Relate the horizontal scale factor to the period. - Use the x-axis labels in multiples of \(\pi\).

Solution

1. The graph has a maximum of \(2\) and a minimum of \(-2\), so the amplitude is \(a=2\). 2. One complete cycle has length \(\pi\), so the period is \(T=\pi\). 3. Use \(b=\frac{2\pi}{T}\): \(b=\frac{2\pi}{\pi}=2\). 4. Therefore, \(f(x)=2\sin(2x)\).

Answer

\(f(x)=2\sin(2x)\)
53353112
The graph belongs to a function of the form \(h(x)=a\sin(x)+d\). Find \(a\) and \(d\) from the graph. The x-axis is scaled in units of \(\pi\).
Figure for problem 533531

Hints

- Find the midline first to determine the vertical shift. - The amplitude is the distance from the midline to a maximum or minimum. - Compare the cycle length with the parent sine function.

Solution

1. The maximum is \(2\) and the minimum is \(-1\), so the midline is \(\frac{2+(-1)}{2}=0.5\). Thus, \(d=0.5\). 2. The amplitude is the distance from the midline to an extreme value: \(2-0.5=1.5\). Thus, \(a=1.5\). 3. The graph completes one cycle over \(2\pi\), consistent with \(\sin(x)\). 4. Therefore, \(h(x)=1.5\sin(x)+0.5\).

Answer

\(a=1.5\); \(d=0.5\); \(h(x)=1.5\sin(x)+0.5\)
53382612
Each graph has the form \(f(x)=a\sin(bx)\). Find \(a\) and \(b\) for each graph. Pay close attention to the direction of the graph at the origin.
Figure for problem 533826

Hints

- A graph that falls through the origin has a negative sine coefficient. - Find the period from corresponding points on consecutive cycles. - Use \(b=\frac{2\pi}{p}\).

Solution

1. Graph a) falls through the origin, so \(a\) is negative. Its amplitude is \(2\), so \(a=-2\). The period is \(2\), so \(b=\frac{2\pi}{2}=\pi\). 2. Graph b) has amplitude \(3\) and period \(5\). Thus, \(a=3\), and \(b=\frac{2\pi}{5}\). 3. Graph c) has amplitude \(1\) and period \(0.5\). Thus, \(a=1\), and \(b=\frac{2\pi}{0.5}=4\pi\).

Answer

a) \(a=-2\), \(b=\pi\) b) \(a=3\), \(b=\frac{2\pi}{5}\) c) \(a=1\), \(b=4\pi\)
53382712
The graph shows \(f(x)=\cos(x)\). One grid interval on the x-axis represents \(\frac{\pi}{6}\). Find the coordinates of points \(A\), \(B\), \(C\), and \(D\).
Figure for problem 533827

Hints

- Count grid intervals to find each x-coordinate. - Each horizontal grid interval represents \(\frac{\pi}{6}\). - Substitute the x-coordinate into \(f(x)=\cos(x)\). - Recall special cosine values.

Solution

1. Read the x-coordinates from the grid: \(x_A=-\frac{\pi}{2}\), \(x_B=0\), \(x_C=\frac{\pi}{3}\), and \(x_D=\pi\). 2. Evaluate cosine at each x-coordinate: \(\cos\left(-\frac{\pi}{2}\right)=0\), \(\cos(0)=1\), \(\cos\left(\frac{\pi}{3}\right)=\frac{1}{2}\), and \(\cos(\pi)=-1\). 3. Therefore, \(A=\left(-\frac{\pi}{2}, 0\right)\), \(B=(0, 1)\), \(C=\left(\frac{\pi}{3}, \frac{1}{2}\right)\), and \(D=(\pi, -1)\).

Answer

\(A=\left(-\frac{\pi}{2}, 0\right)\), \(B=(0, 1)\), \(C=\left(\frac{\pi}{3}, \frac{1}{2}\right)\), and \(D=(\pi, -1)\)
53382812
The graph shows \(f(x)=\cos(x)-1\). One grid interval on the x-axis represents \(\frac{\pi}{2}\). Give the coordinates of points \(A\), \(B\), \(C\), and \(D\).
Figure for problem 533828

Hints

- Count grid intervals to find the x-coordinates. - Substitute each x-coordinate into \(f(x)=\cos(x)-1\). - Check the points against the graph.

Solution

1. Reading the x-coordinates from the grid gives \(x_A=0\), \(x_B=\frac{\pi}{2}\), \(x_C=\pi\), and \(x_D=2\pi\). 2. Evaluate the function: \(f(0)=0\), \(f\left(\frac{\pi}{2}\right)=-1\), \(f(\pi)=-2\), and \(f(2\pi)=0\). 3. Therefore, the points are \(A(0, 0)\), \(B\left(\frac{\pi}{2}, -1\right)\), \(C(\pi, -2)\), and \(D(2\pi, 0)\).

Answer

\(A(0, 0)\), \(B\left(\frac{\pi}{2}, -1\right)\), \(C(\pi, -2)\), \(D(2\pi, 0)\)
53382912
The graph shows \(f(x)=\sin(x)\). One grid interval on the x-axis represents \(\frac{\pi}{6}\). Find the coordinates of points \(A\), \(B\), \(C\), and \(D\).
Figure for problem 533829

Hints

- Each horizontal grid interval represents \(\frac{\pi}{6}\). - Count grid intervals from the origin to obtain each x-coordinate. - Use special-angle sine values for the y-coordinates.

Solution

1. Read the x-coordinates from the grid: \(x_A=0\), \(x_B=\frac{\pi}{6}\), \(x_C=\frac{\pi}{2}\), and \(x_D=\frac{3\pi}{2}\). 2. Evaluate sine at each x-coordinate: \(\sin(0)=0\), \(\sin\left(\frac{\pi}{6}\right)=\frac{1}{2}\), \(\sin\left(\frac{\pi}{2}\right)=1\), and \(\sin\left(\frac{3\pi}{2}\right)=-1\). 3. Therefore, the points are \(A=(0, 0)\), \(B=\left(\frac{\pi}{6}, \frac{1}{2}\right)\), \(C=\left(\frac{\pi}{2}, 1\right)\), and \(D=\left(\frac{3\pi}{2}, -1\right)\).

Answer

\(A=(0, 0)\), \(B=\left(\frac{\pi}{6}, \frac{1}{2}\right)\), \(C=\left(\frac{\pi}{2}, 1\right)\), and \(D=\left(\frac{3\pi}{2}, -1\right)\)
53383012
The graph shows a function of the form \(f(x)=a\sin(x)\). One grid interval on the x-axis represents \(\frac{\pi}{2}\). First determine \(a\), and then give the coordinates of points \(A\), \(B\), \(C\), and \(D\).
Figure for problem 533830

Hints

- The parameter \(a\) is the amplitude, the maximum distance from the midline. - Count grid intervals on the x-axis, with each interval representing \(\frac{\pi}{2}\). - After finding \(a\), substitute the read x-values into \(f(x)=a\sin(x)\).

Solution

1. The first maximum occurs at \(x=\frac{\pi}{2}\) and has y-coordinate \(2\). Since \(\sin\left(\frac{\pi}{2}\right)=1\), \(a=2\), so \(f(x)=2\sin(x)\). 2. Reading the x-coordinates from the grid gives \(x_A=0\), \(x_B=\frac{\pi}{2}\), \(x_C=\pi\), and \(x_D=\frac{3\pi}{2}\). 3. Evaluating the function gives \(A(0, 0)\), \(B\left(\frac{\pi}{2}, 2\right)\), \(C(\pi, 0)\), and \(D\left(\frac{3\pi}{2}, -2\right)\).

Answer

\(a=2\); \(A(0, 0)\), \(B\left(\frac{\pi}{2}, 2\right)\), \(C(\pi, 0)\), \(D\left(\frac{3\pi}{2}, -2\right)\)
53385312
The graph shows \(f(x)=\sin\left(\frac{\pi}{2}x\right)\). Find the coordinates of the marked points \(A\), \(B\), \(C\), and \(D\).
Figure for problem 533853

Hints

- Identify whether each marked point is a maximum, minimum, or zero. - Read each x-coordinate from the grid. - Substitute the x-coordinate into the function to verify the y-coordinate. - Recall sine values at multiples of \(\frac{\pi}{2}\).

Solution

1. Point \(A\) is the first maximum. Since \(\sin\left(\frac{\pi}{2}\cdot1\right)=1\), \(A=(1, 1)\). 2. Point \(B\) is the first zero after the origin. Since \(\sin\left(\frac{\pi}{2}\cdot2\right)=\sin(\pi)=0\), \(B=(2, 0)\). 3. Point \(C\) is the first minimum. Since \(\sin\left(\frac{\pi}{2}\cdot3\right)=\sin\left(\frac{3\pi}{2}\right)=-1\), \(C=(3, -1)\). 4. Point \(D\) is the next zero. Since \(\sin\left(\frac{\pi}{2}\cdot4\right)=\sin(2\pi)=0\), \(D=(4, 0)\).

Answer

\(A=(1, 1)\), \(B=(2, 0)\), \(C=(3, -1)\), and \(D=(4, 0)\)
53402012
The graph shows several members of the family \(g_a(x)=a\cos(x)\). State the equation of the family and identify the values of \(a\) used for the displayed graphs.
Figure for problem 534020

Hints

- What is \(\cos(0)\)? - A coefficient outside cosine determines the amplitude. - Read the graphs' y-values at \(x=0\).

Solution

1. Each graph has the shape and period of a cosine function, so the family has the form \(g_a(x)=a\cos(x)\). 2. Since \(\cos(0)=1\), each graph has \(g_a(0)=a\). 3. Reading the y-values at \(x=0\) gives \(0.5\), \(1\), \(2\), and \(3\). 4. Therefore, \(a \in \{0.5, 1, 2, 3\}\).

Answer

\(g_a(x)=a\cos(x)\), with \(a \in \{0.5, 1, 2, 3\}\)
53432712
The function \(h\) is obtained from \(f(x)=\sin(x)\) by a horizontal compression by a factor of \(\frac{1}{3}\), so \(b=3\), and a vertical compression by a factor of \(0.75\). a) Write the function \(h(x)\). b) Find the amplitude and period of \(h\).
Figure for problem 534327

Hints

- In \(a\sin(bx)\), identify the roles of \(a\) and \(b\). - Relate the horizontal compression to the length of one complete cycle.

Solution

1. Use \(a=0.75\) and \(b=3\): \(h(x)=0.75\sin(3x)\). 2. The amplitude is \(A=0.75\). 3. The period is \(p=\frac{2\pi}{3}\).

Answer

a) \(h(x)=0.75\sin(3x)\) b) Amplitude: \(0.75\); period: \(\frac{2\pi}{3}\)
53460312
Match graphs 1, 2, and 3 to the functions. Briefly justify each match using a transformation or a key point. \(p(x)=2\cos x\) \(q(x)=\sin(x-1)\) \(r(x)=\cos x-2\)
Figure for problem 534603

Hints

- Compare amplitudes and midlines. - Check the value of each function at \(x=0\) or another simple input. - Identify horizontal and vertical shifts from key points. - Determine whether each graph has the shape of sine or cosine.

Solution

1. Graph 1 has amplitude \(2\) and value \(2\) at \(x=0\), so it matches \(p(x)=2\cos x\). 2. Graph 2 is a sine curve shifted right \(1\) unit. It crosses its midline at \(x=1\), so it matches \(q(x)=\sin(x-1)\). 3. Graph 3 is a cosine curve with midline \(y=-2\). It is shifted down \(2\) units, so it matches \(r(x)=\cos x-2\).

Answer

Graph 1: \(p(x)\) Graph 2: \(q(x)\) Graph 3: \(r(x)\)
52184512
Let \(f(x)=\cos(x)\). a) The graph of \(f\) is vertically stretched by a factor of \(2\) and then shifted right \(\pi\) units to produce the graph of \(g\). Write a rule for \(g\). b) State the amplitude and period of \(g\). c) Give one positive value and one negative value of \(d\) for which \(g(x)=2\cos(x+d)\) for every real \(x\).

Hints

- A horizontal shift changes the input inside the cosine function. - In \(a\cos(b(x-c))+d\), identify which parameter controls amplitude and which controls period. - Use the periodicity of cosine to find equivalent phase shifts.

Solution

1. A vertical stretch by a factor of \(2\) and a shift right \(\pi\) units give \(g(x)=2\cos(x-\pi)\). 2. The amplitude is \(|2|=2\). The coefficient of \(x\) is \(1\), so the period remains \(2\pi\). 3. The rule from part a gives \(d=-\pi\). Since cosine has period \(2\pi\), \(\cos(x-\pi)=\cos(x+\pi)\), so \(d=\pi\) also works.

Answer

a) \(g(x)=2\cos(x-\pi)\) b) Amplitude: \(2\); period: \(2\pi\) c) \(d=\pi\) and \(d=-\pi\)
52184612
Let \(p(x)=\sin(x)\). a) The graph of \(p\) is horizontally stretched by a factor of \(3\) and shifted up \(2\) units to produce the graph of \(q\). Write a rule for \(q\) and state its range. b) Find the period of \(q\). c) Find a value of \(c\) in \([0, 2\pi]\) such that \(q(x)=\cos\left(\frac{1}{3}x-c\right)+2\) for every real \(x\).

Hints

- A horizontal stretch changes the coefficient of \(x\) inside the function. - Start with the maximum and minimum values of sine, then apply the vertical shift. - Use a phase-shift identity relating sine and cosine.

Solution

1. A horizontal stretch by a factor of \(3\) replaces \(x\) with \(\frac{1}{3}x\). Shifting up \(2\) units gives \(q(x)=\sin\left(\frac{1}{3}x\right)+2\). Since sine has range \([-1, 1]\), the range of \(q\) is \([1, 3]\). 2. For \(\sin(bx)\), the period is \(\frac{2\pi}{|b|}\). Here, \(b=\frac{1}{3}\), so the period is \(\frac{2\pi}{1/3}=6\pi\). 3. Use \(\sin(\alpha)=\cos\left(\alpha-\frac{\pi}{2}\right)\). With \(\alpha=\frac{1}{3}x\), this gives \(q(x)=\cos\left(\frac{1}{3}x-\frac{\pi}{2}\right)+2\), so \(c=\frac{\pi}{2}\).

Answer

a) \(q(x)=\sin\left(\frac{1}{3}x\right)+2\); range: \([1, 3]\) b) \(6\pi\) c) \(c=\frac{\pi}{2}\)
52185512
The function \(f(x)=2\sin(3x-\pi)+1\) is a transformation of the parent function \(g(x)=\sin(x)\). Describe a sequence of transformations that produces the graph of \(f\) from the graph of \(g\).

Hints

- Factor the coefficient of \(x\) from the entire angle expression. - Identify the parameters that control horizontal scale, phase shift, amplitude, and vertical shift. - Distinguish transformations applied to the input from those applied to the output. - Replacing \(x\) with \(3x\) changes the horizontal scale.

Solution

1. Factor the argument: \(3x-\pi=3\left(x-\frac{\pi}{3}\right)\), so \(f(x)=2\sin\left(3\left(x-\frac{\pi}{3}\right)\right)+1\). 2. Horizontally compress the graph of \(g\) by a factor of \(\frac{1}{3}\). 3. Shift the result right \(\frac{\pi}{3}\) units. 4. Vertically stretch by a factor of \(2\). 5. Shift up \(1\) unit.

Answer

Horizontally compress by a factor of \(\frac{1}{3}\), shift right \(\frac{\pi}{3}\) units, vertically stretch by a factor of \(2\), and shift up \(1\) unit.
52260012
Let \(k(x)=1.5\sin(x+2)-3\). Describe the transformations that produce the graph of \(k\) from the graph of \(f(x)=\sin(x)\). Then state the amplitude and range of \(k\).

Hints

- Compare the rule with \(a\sin(x-c)+d\). - Pay attention to the sign of the horizontal shift inside the input. - Use the amplitude and midline to find the highest and lowest values. - The range contains all possible output values.

Solution

1. The factor \(1.5\) creates a vertical stretch by a factor of \(1.5\). 2. The input \(x+2\) shifts the graph left \(2\) units. 3. The term \(-3\) shifts the graph down \(3\) units. 4. The amplitude is \(|1.5|=1.5\). 5. Sine has range \([-1, 1]\). After the vertical stretch, the range is \([-1.5, 1.5]\), and after shifting down \(3\), the range is \([-4.5, -1.5]\).

Answer

Transformations: vertically stretch by a factor of \(1.5\), shift left \(2\) units, and shift down \(3\) units. Amplitude: \(1.5\) Range: \([-4.5, -1.5]\)
52370712
The graph of \(g\) is obtained from \(f(x)=\cos(x)\) by a vertical stretch by a factor of \(2.5\), a reflection across the x-axis, and a downward shift of \(1.5\) units. Write \(g(x)\), and give its amplitude and range.

Hints

- Track how the vertical stretch and reflection affect the outside coefficient. - A vertical shift is added outside the cosine expression. - Amplitude is a positive distance from the midline. - Use the midline and amplitude to find the minimum and maximum values.

Solution

1. The vertical stretch gives \(2.5\cos(x)\). 2. Reflecting across the x-axis gives \(-2.5\cos(x)\). 3. Shifting down \(1.5\) units gives \(g(x)=-2.5\cos(x)-1.5\). 4. The amplitude is \(|-2.5|=2.5\). 5. The midline is \(y=-1.5\), so the range is \([-1.5-2.5, -1.5+2.5]=[-4, 1]\).

Answer

\(g(x)=-2.5\cos(x)-1.5\); amplitude: \(2.5\); range: \([-4, 1]\)
52371712
The graph of \(f(x)=\sin(x)\) has repeating symmetries. a) Explain why \(x=\frac{3\pi}{2}\) is an axis of symmetry of the graph. b) Give another axis of symmetry in \([0, \pi]\). c) The graph is point-symmetric about each x-intercept. Give the coordinates of three different centers of symmetry in \([-\pi, 2\pi]\).

Hints

- Locate the maximum and minimum points of the sine graph. - Compare the graph immediately to the left and right of an extremum. - Recall where the sine graph crosses the x-axis. - Use the repeating shape of the sine graph to identify line and point symmetries.

Solution

1. At \(x=\frac{3\pi}{2}\), sine has a local minimum of \(-1\). The graph has mirror symmetry to the left and right of this minimum, so \(x=\frac{3\pi}{2}\) is an axis of symmetry. 2. In \([0, \pi]\), sine has a maximum at \(x=\frac{\pi}{2}\), so \(x=\frac{\pi}{2}\) is another axis of symmetry. 3. The zeros of sine occur at \(x=k\pi\). In the given interval, possible centers are \((-\pi, 0)\), \((0, 0)\), \((\pi, 0)\), and \((2\pi, 0)\). Any three are valid.

Answer

a) The line \(x=\frac{3\pi}{2}\) passes through a minimum, and the graph mirrors across that vertical line. b) \(x=\frac{\pi}{2}\) c) For example, \((-\pi, 0)\), \((0, 0)\), and \((\pi, 0)\)
52371812
Analyze the symmetries of \(g(x)=\cos(x)\). a) Show algebraically that the graph is symmetric about the y-axis. b) Find every vertical line \(x=a\) in \([0, 3\pi]\) across which the graph can be reflected onto itself. c) Give the coordinates of all centers of rotational symmetry whose x-coordinates lie in \([0, 2\pi]\).

Hints

- Recall the definition of an even function. - Vertical symmetry lines pass through maxima and minima of the cosine graph. - Centers of rotational symmetry occur at x-intercepts. - Check the stated interval endpoints carefully.

Solution

1. For a), \(g(-x)=\cos(-x)=\cos(x)=g(x)\). Therefore, cosine is even, and its graph is symmetric about the y-axis. 2. The maxima and minima of cosine occur at \(x=k\pi\), and each such vertical line is an axis of symmetry. In \([0, 3\pi]\), the axes are \(x=0\), \(x=\pi\), \(x=2\pi\), and \(x=3\pi\). 3. The centers of rotational symmetry occur at the x-intercepts \(x=\frac{\pi}{2}+k\pi\). In \([0, 2\pi]\), they are \(\left(\frac{\pi}{2}, 0\right)\) and \(\left(\frac{3\pi}{2}, 0\right)\).

Answer

a) \(g(-x)=g(x)\), so the graph is symmetric about the y-axis. b) \(x=0\), \(x=\pi\), \(x=2\pi\), and \(x=3\pi\) c) \(\left(\frac{\pi}{2}, 0\right)\) and \(\left(\frac{3\pi}{2}, 0\right)\)
52372412
For each description, write a function of the form \(f(x)=a\cos(bx)\), where \(a>0\) and \(b>0\). a) The amplitude is \(1.5\), and the period is \(4\pi\). b) The amplitude is \(4\), and the period is \(1\). c) The graph oscillates symmetrically about the x-axis between \(-2\) and \(2\), and one complete cycle has length \(3\).

Hints

- Match the given amplitude and period to the parameters \(a\) and \(b\). - The amplitude is the maximum distance from the midline. - Rearrange \(p=\frac{2\pi}{b}\) to solve for \(b\). - A graph that ranges from \(-2\) to \(2\) has amplitude \(2\).

Solution

1. For part a, \(a=1.5\). Using \(p=\frac{2\pi}{b}\), solve \(4\pi=\frac{2\pi}{b}\) to get \(b=0.5\). Thus, \(f(x)=1.5\cos(0.5x)\). 2. For part b, \(a=4\). Solve \(1=\frac{2\pi}{b}\) to get \(b=2\pi\). Thus, \(f(x)=4\cos(2\pi x)\). 3. For part c, the range \([-2, 2]\) gives \(a=2\). Solve \(3=\frac{2\pi}{b}\) to get \(b=\frac{2\pi}{3}\). Thus, \(f(x)=2\cos\left(\frac{2\pi}{3}x\right)\).

Answer

a) \(f(x)=1.5\cos(0.5x)\) b) \(f(x)=4\cos(2\pi x)\) c) \(f(x)=2\cos\left(\frac{2\pi}{3}x\right)\)
52372712
A sine function has the form \(f(x)=a\sin(bx)\), where \(a>0\) and \(b>0\). Its amplitude is \(4.5\), and its first positive zero is \(x=3\). Find \(a\), \(b\), and the function.

Hints

- Relate the parameter \(a\) to the amplitude. - Recall where the zeros of the parent sine function occur. - Use the relationship between period \(p\) and parameter \(b\). - Determine what fraction of a period lies between the origin and the first positive zero.

Solution

1. The amplitude gives \(a=4.5\). 2. For \(\sin(bx)\), the first positive zero occurs after half a period. Thus, \(\frac{p}{2}=3\), so \(p=6\). 3. Use \(b=\frac{2\pi}{p}\): \(b=\frac{2\pi}{6}=\frac{\pi}{3}\). 4. Therefore, \(f(x)=4.5\sin\left(\frac{\pi}{3}x\right)\).

Answer

\(a=4.5\); \(b=\frac{\pi}{3}\); \(f(x)=4.5\sin\left(\frac{\pi}{3}x\right)\)
52372812
The function \(g(x)=a\sin(bx)\), where \(a>0\) and \(b>0\), models an oscillation. The distance between consecutive maximum points is \(\pi\), and the graph passes through \(P\left(\frac{\pi}{4},5\right)\). Find \(a\), \(b\), and the function.

Hints

- The distance between consecutive maximum points equals the period. - Use the period to determine \(b\). - Substitute the given point to find the remaining parameter. - Recall the value of \(\sin\left(\frac{\pi}{2}\right)\).

Solution

1. The distance between consecutive maximum points is the period, so \(p=\pi\). 2. Use \(b=\frac{2\pi}{p}\): \(b=\frac{2\pi}{\pi}=2\). Thus, \(g(x)=a\sin(2x)\). 3. Substitute the point: \(5=a\sin\left(2\cdot \frac{\pi}{4}\right)=a\sin\left(\frac{\pi}{2}\right)\). 4. Since \(\sin\left(\frac{\pi}{2}\right)=1\), \(a=5\). Therefore, \(g(x)=5\sin(2x)\).

Answer

\(a=5\); \(b=2\); \(g(x)=5\sin(2x)\)
52373412
A graph is obtained from \(f(x)=\sin(x)\) by the following transformations: - reflection across the x-axis, - vertical stretch to amplitude \(2.5\), - change of period to \(4\), - shift up \(1\) unit. Find the resulting function \(h(x)\).

Hints

- Combine the amplitude and reflection in the outside coefficient. - Use the period formula to determine the coefficient inside sine. - The outside constant controls the vertical shift. - Substitute the parameters into \(a\sin(bx)+d\).

Solution

1. The amplitude and reflection give the outside coefficient \(a=-2.5\). 2. The period \(p=4\) gives \(b=\frac{2\pi}{p}=\frac{\pi}{2}\). 3. The upward shift gives \(d=1\). 4. Therefore, \(h(x)=-2.5\sin\left(\frac{\pi}{2}x\right)+1\).

Answer

\(h(x)=-2.5\sin\left(\frac{\pi}{2}x\right)+1\)
52373612
Determine whether each statement is true. Justify your answer and correct any false statement. a) The graph of \(f(x)=\sin(2x-6)\) is shifted \(6\) units right from the graph of \(g(x)=\sin(2x)\). b) The function \(h(x)=\sin(x)+2\) has the same range as \(k(x)=2\sin(x)\). c) The graphs of \(p(x)=\sin(x-\pi)\) and \(q(x)=-\sin(x)\) are identical.

Hints

- Factor the coefficient of \(x\) before reading a horizontal shift. - Find the minimum and maximum values of each function. - Consider the effect of shifting a sine graph by half a period.

Solution

1. Factor the input: \(\sin(2x-6)=\sin(2(x-3))\). The shift is \(3\) units right, so statement a is false. 2. The range of \(h\) is \([1, 3]\), while the range of \(k\) is \([-2, 2]\). The ranges differ, so statement b is false. 3. A shift by half a period reverses the sign of sine: \(\sin(x-\pi)=-\sin(x)\). Therefore, statement c is true.

Answer

a) False. The graph is shifted \(3\) units right because \(f(x)=\sin(2(x-3))\). b) False. The ranges are \([1, 3]\) and \([-2, 2]\), respectively. c) True.
52375212
The graph of a periodic function of the form \(g(x)=a\sin(b(x-c))+d\) crosses its midline at \((0, 2)\) while increasing. Its next maximum is \((2, 5)\). Find an equation for \(g\).

Hints

- Use the midline crossing to determine \(c\) and \(d\). - Find the amplitude from the maximum value and the midline. - The distance from an increasing midline crossing to the next maximum is one-fourth of a period. - Use the period to determine \(b\).

Solution

1. Because \((0,2)\) lies on the midline, \(d=2\). 2. The amplitude is the difference between the maximum value and the midline: \(a=5-2=3\). 3. The distance from an increasing midline crossing to the next maximum is one-fourth of a period. Thus, \(\frac{p}{4}=2\), so \(p=8\). 4. Therefore, \(b=\frac{2\pi}{8}=\frac{\pi}{4}\). 5. The increasing midline crossing occurs at \(x=0\), so take \(c=0\). Therefore, \(g(x)=3\sin\left(\frac{\pi}{4}x\right)+2\).

Answer

\(g(x)=3\sin\left(\frac{\pi}{4}x\right)+2\)
52858212
The zeros of \(f(x)=\cos(x)\) occur at regular intervals. a) Find all zeros on \([0, 2\pi]\). b) Use periodicity to find all zeros on \([-2\pi, 3\pi]\). c) How many zeros are in \([-2\pi, 3\pi]\)?

Hints

- Cosine is zero when the unit-circle x-coordinate is \(0\). - Consecutive cosine zeros are \(\pi\) units apart. - Test values of \(\frac{\pi}{2}+k\pi\) against the interval. - Include both positive and negative values of \(k\).

Solution

1. In \([0, 2\pi]\), cosine is zero at \(x=\frac{\pi}{2}\) and \(x=\frac{3\pi}{2}\). 2. In general, the zeros are \(x=\frac{\pi}{2}+k\pi\), where \(k \in \mathbb{Z}\). 3. Testing integer values of \(k\) for \([-2\pi, 3\pi]\) gives \(-\frac{3\pi}{2}\), \(-\frac{\pi}{2}\), \(\frac{\pi}{2}\), \(\frac{3\pi}{2}\), and \(\frac{5\pi}{2}\). 4. There are \(5\) zeros.

Answer

a) \(x=\frac{\pi}{2}\) and \(x=\frac{3\pi}{2}\) b) \(x \in \left\{-\frac{3\pi}{2}, -\frac{\pi}{2}, \frac{\pi}{2}, \frac{3\pi}{2}, \frac{5\pi}{2}\right\}\) c) \(5\) zeros
52859112
Consider \(f(x)=\sin(x)\) on \([-\pi, \pi]\). a) Find the x-coordinates of the interior local maximum and minimum. b) State the subinterval on which the function is strictly increasing. c) State the subintervals on which the function is strictly decreasing.

Hints

- Locate the maximum and minimum points of the sine graph. - Think about where the graph rises as \(x\) increases. - Think about where the graph falls as \(x\) increases. - Restrict every interval to the given domain.

Solution

1. On \([-\pi, \pi]\), sine reaches its minimum value \(-1\) at \(x=-\frac{\pi}{2}\) and its maximum value \(1\) at \(x=\frac{\pi}{2}\). 2. From \(x=-\frac{\pi}{2}\) to \(x=\frac{\pi}{2}\), the function rises from \(-1\) to \(1\), so it is strictly increasing on \(\left[-\frac{\pi}{2}, \frac{\pi}{2}\right]\). 3. The function is strictly decreasing on \(\left[-\pi, -\frac{\pi}{2}\right]\) and \(\left[\frac{\pi}{2}, \pi\right]\).

Answer

a) Minimum at \(x=-\frac{\pi}{2}\); maximum at \(x=\frac{\pi}{2}\) b) \(\left[-\frac{\pi}{2}, \frac{\pi}{2}\right]\) c) \(\left[-\pi, -\frac{\pi}{2}\right]\) and \(\left[\frac{\pi}{2}, \pi\right]\)
52859212
Consider \(g(x)=\cos(x)\) for angles from \(0^\circ\) to \(360^\circ\). a) State the intervals on which cosine is strictly decreasing and strictly increasing. b) Without a calculator, decide whether \(\cos(110^\circ)>\cos(160^\circ)\). Justify your answer using part a).

Hints

- Track the unit-circle x-coordinate as the angle increases. - Locate the maximum and minimum values of cosine. - Recall what strictly decreasing means when comparing two inputs. - Determine which monotonicity interval contains both angles.

Solution

1. From \(0^\circ\) to \(180^\circ\), cosine decreases from \(1\) to \(-1\), so it is strictly decreasing on \([0^\circ, 180^\circ]\). 2. From \(180^\circ\) to \(360^\circ\), cosine increases from \(-1\) to \(1\), so it is strictly increasing on \([180^\circ, 360^\circ]\). 3. Both \(110^\circ\) and \(160^\circ\) lie in the decreasing interval. Since \(110^\circ < 160^\circ\), it follows that \(\cos(110^\circ)>\cos(160^\circ)\).

Answer

a) Strictly decreasing on \([0^\circ, 180^\circ]\); strictly increasing on \([180^\circ, 360^\circ]\) b) True; \(110^\circ < 160^\circ\) and cosine is decreasing on that interval.
52859812
Let \(g(x)=\sin(0.5x)\). The function reaches its maximum value \(1\) at \(x=\pi\). a) Find the period \(p\) of \(g\). b) Give four other values of \(x\) where \(g(x)=1\).

Hints

- Identify the coefficient of \(x\) inside the sine function. - Use the period formula for \(\sin(bx)\). - Maximum points repeat after each full period.

Solution

1. For \(\sin(bx)\), the period is \(p=\frac{2\pi}{|b|}\). With \(b=0.5\), \(p=\frac{2\pi}{0.5}=4\pi\). 2. Maximum points repeat every period, so all such inputs have the form \(x=\pi+4\pi k\), where \(k\) is an integer. 3. Using \(k=1, 2, -1, -2\) gives \(5\pi, 9\pi, -3\pi, -7\pi\).

Answer

a) \(p=4\pi\) b) For example, \(-7\pi, -3\pi, 5\pi, 9\pi\)
52860512
A function of the form \(f(x)=a\sin(bx)\) has amplitude \(5\) and period \(120^\circ\). Find all zeros of the function in the interval \(0^\circ \leq x \leq 180^\circ\).

Hints

- Use the period to determine the coefficient of \(x\). - A zero occurs when the sine value is \(0\). - Recall the spacing between consecutive zeros of the parent sine function. - Check each result against the stated interval.

Solution

1. The amplitude gives \(a=5\). The period gives \(b=\frac{360^\circ}{120^\circ}=3\), so \(f(x)=5\sin(3x)\). 2. Set \(5\sin(3x)=0\), which is equivalent to \(\sin(3x)=0\). 3. Sine is zero when \(3x=180^\circ k\), where \(k\) is an integer. Thus, \(x=60^\circ k\). 4. In the given interval, the zeros are \(0^\circ, 60^\circ, 120^\circ, 180^\circ\).

Answer

\(x=0^\circ, 60^\circ, 120^\circ, 180^\circ\)
52861512
Consider \(f(x)=\sin(x)\) on \([0, 2\pi]\). Determine the number of solutions to \(f(x)=c\) for each value of \(c\). a) \(c=1\) b) \(c=0.8\) c) \(c=0\) d) \(c=-1\) e) \(c=-2\) Why are there more solutions for \(c=0\) than for \(c=1\)? Explain using the graph.

Hints

- Recall the minimum and maximum values of sine. - Visualize the graph from \(0\) to \(2\pi\). - Include both endpoints because the interval is closed. - Count intersections with each horizontal line.

Solution

1. The range of sine is \([-1, 1]\). 2. For a), the horizontal line \(y=1\) touches the graph once, at \(x=\frac{\pi}{2}\). 3. For b), the line \(y=0.8\) intersects the graph twice. 4. For c), the line \(y=0\) intersects the graph at \(x=0\), \(x=\pi\), and \(x=2\pi\), for three solutions. 5. For d), the line \(y=-1\) touches the graph once, at \(x=\frac{3\pi}{2}\). 6. For e), \(-2\) is outside the range of sine, so there are no solutions. 7. The value \(0\) occurs at both endpoints and at the midpoint of the closed interval, while the maximum value \(1\) occurs at only one point.

Answer

a) \(1\) solution b) \(2\) solutions c) \(3\) solutions d) \(1\) solution e) \(0\) solutions There are three solutions for \(c=0\) because the graph meets the x-axis at \(0\), \(\pi\), and \(2\pi\), while it reaches its maximum only once.
52861612
How many solutions does \(\cos(x)=k\) have on \([0, 2\pi]\)? Fill in each blank. 1. If \(k < -1\) or \(k > 1\), the number of solutions is ___. 2. If \(k=-1\), the number of solutions is ___. The solution is \(x=\) ___. 3. If \(-1 < k < 1\), the number of solutions is ___. 4. If \(k=1\), the number of solutions is ___. The solutions are \(x_1=\) ___ and \(x_2=\) ___.

Hints

- Use the range of cosine. - Consider one complete cosine period from \(0\) to \(2\pi\). - Count intersections with horizontal lines. - Remember that both interval endpoints are included.

Solution

1. The range of cosine is \([-1, 1]\), so there are no solutions when \(|k|>1\). 2. The minimum value \(-1\) occurs once on the interval, at \(x=\pi\). 3. Every value strictly between \(-1\) and \(1\) occurs twice in one closed period. 4. The maximum value \(1\) occurs at both endpoints, \(x=0\) and \(x=2\pi\), so there are two solutions.

Answer

1. \(0\) 2. \(1\); \(x=\pi\) 3. \(2\) 4. \(2\); \(x_1=0\), \(x_2=2\pi\)
52861712
Let \(f(x)=a\sin(x)\). Find \(a\) for each condition. a) The range is \([-2.5, 2.5]\), and \(a>0\). b) The graph passes through \(P\left(\frac{3\pi}{4}, 3\sqrt{2}\right)\).

Hints

- Relate the outside coefficient to the amplitude and range. - Recall the minimum and maximum values of the parent sine function. - A point on the graph satisfies the function equation. - Use the exact unit-circle value at \(\frac{3\pi}{4}\).

Solution

1. The range of \(a\sin(x)\) is \([-|a|, |a|]\). Part a gives \(|a|=2.5\), and the condition \(a>0\) gives \(a=2.5\). 2. For part b, substitute the point: \(3\sqrt{2}=a\sin\left(\frac{3\pi}{4}\right)\). 3. Since \(\sin\left(\frac{3\pi}{4}\right)=\frac{\sqrt{2}}{2}\), solve \(3\sqrt{2}=a\frac{\sqrt{2}}{2}\) to obtain \(a=6\).

Answer

a) \(a=2.5\) b) \(a=6\)
52861812
Let \(g(x)=k\cos(x)\). Find \(k\) for each condition. a) The distance from the minimum function value to the maximum function value is \(24\). Give all possible values of \(k\). b) \(g\left(\frac{4\pi}{3}\right)=2\).

Hints

- The total vertical range is twice the amplitude. - Reflecting across the x-axis does not change the range. - Use the unit circle to evaluate cosine at \(\frac{4\pi}{3}\). - Substitute the given input and output, then solve the resulting linear equation.

Solution

1. The minimum and maximum are \(-|k|\) and \(|k|\), so their distance is \(2|k|\). 2. For part a, \(2|k|=24\), so \(|k|=12\) and \(k=12\) or \(k=-12\). 3. For part b, \(k\cos\left(\frac{4\pi}{3}\right)=2\). Since \(\cos\left(\frac{4\pi}{3}\right)=-\frac{1}{2}\), solve \(-\frac{k}{2}=2\) to get \(k=-4\).

Answer

a) \(k=12\) or \(k=-12\) b) \(k=-4\)
52862512
Consider the cosine function \(y=\cos(kx)\), where \(k>0\). a) Find \(k\) if the period is \(5\pi\). b) The graph passes through \(P\left(\frac{\pi}{4}, -\frac{\sqrt{2}}{2}\right)\). Find the least possible positive value of \(k\).

Hints

- Relate the period of cosine to the coefficient of \(x\). - Substitute the coordinates of a point that lies on the graph. - Identify the unit-circle angles with the required cosine value. - Solve the resulting equation for \(k\).

Solution

1. The period is \(p=\frac{2\pi}{k}\). 2. For part a, solve \(5\pi=\frac{2\pi}{k}\) to obtain \(k=\frac{2}{5}=0.4\). 3. For part b, substitute the point: \(\cos\left(\frac{k\pi}{4}\right)=-\frac{\sqrt{2}}{2}\). 4. The least positive angle with this cosine value is \(\frac{3\pi}{4}\). Therefore, \(\frac{k\pi}{4}=\frac{3\pi}{4}\), so \(k=3\).

Answer

a) \(k=0.4\) b) \(k=3\)
52862812
Consider \(g(x)=0.5\sin(2x)\) on \(0 \leq x \leq \pi\). Find the amplitude, period, all zeros, and the coordinates of the maximum and minimum points in this interval.

Hints

- Find the period first to determine how much of the graph appears in the interval. - Set the sine input equal to integer multiples of \(\pi\) to find zeros. - Recall where the parent sine function reaches its maximum and minimum. - Verify that every input lies in the stated interval.

Solution

1. The amplitude is \(0.5\), and the period is \(p=\frac{2\pi}{2}=\pi\). 2. Zeros occur when \(2x=k\pi\). In the interval, this gives \(x=0, \frac{\pi}{2}, \pi\). 3. The maximum occurs when \(2x=\frac{\pi}{2}\), so \(x=\frac{\pi}{4}\) and \(g(x)=0.5\). The maximum point is \(\left(\frac{\pi}{4}, 0.5\right)\). 4. The minimum occurs when \(2x=\frac{3\pi}{2}\), so \(x=\frac{3\pi}{4}\) and \(g(x)=-0.5\). The minimum point is \(\left(\frac{3\pi}{4}, -0.5\right)\).

Answer

Amplitude: \(0.5\); period: \(\pi\); zeros: \(0, \frac{\pi}{2}, \pi\); maximum: \(\left(\frac{\pi}{4}, 0.5\right)\); minimum: \(\left(\frac{3\pi}{4}, -0.5\right)\)
52862912
Describe the transformations from \(y=\sin(x)\) to \(f(x)=0.5\sin\left(2x+\frac{\pi}{2}\right)-1\).

Hints

- Factor the coefficient of \(x\) from the entire input before reading the horizontal shift. - Interpret the parameters in \(a\sin(b(x-c))+d\). - An inside coefficient greater than \(1\) horizontally compresses the graph.

Solution

1. Factor the input: \(f(x)=0.5\sin\left(2\left(x+\frac{\pi}{4}\right)\right)-1\). 2. The outside factor \(0.5\) gives a vertical compression by \(0.5\). 3. The inside factor \(2\) gives a horizontal compression by \(\frac{1}{2}\), so the period is \(\pi\). 4. The term \(x+\frac{\pi}{4}\) shifts the graph left \(\frac{\pi}{4}\). 5. The outside term \(-1\) shifts the graph down \(1\) unit.

Answer

Vertical compression by \(0.5\); horizontal compression by \(\frac{1}{2}\); shift left \(\frac{\pi}{4}\); shift down \(1\).
52863012
Write a cosine function in the form \(g(x)=a\cos(b(x-c))+d\) obtained from \(y=\cos(x)\) by these transformations: - reflect across the x-axis, - vertically stretch by \(3\), - horizontally stretch so that the period doubles, - shift left by \(\pi\), - shift down \(2\) units.

Hints

- Use the period to determine the inside coefficient. - Reflection across the x-axis changes the sign of the outside coefficient. - A left shift appears as addition inside the input.

Solution

1. Reflection and vertical stretch give \(a=-3\). 2. Doubling the parent period gives \(T=4\pi\), so \(b=\frac{2\pi}{4\pi}=0.5\). 3. A shift left by \(\pi\) gives \(x+\pi\), and a shift down \(2\) gives \(d=-2\). 4. Therefore, \(g(x)=-3\cos\left(0.5(x+\pi)\right)-2\).

Answer

\(g(x)=-3\cos\left(0.5(x+\pi)\right)-2\)
52863412
Starting with \(f(x)=\cos(x)\), apply these transformations in order: 1. horizontally stretch by a factor of \(4\), 2. reflect across the x-axis, 3. shift right by \(\pi\). a) Write the resulting function \(h(x)\). b) Determine whether \(P(5\pi, 1)\) lies on the graph.

Hints

- A horizontal stretch changes the function input by the reciprocal factor. - Reflection across the x-axis negates the function value. - Apply the transformations in order. - Substitute the point's x-coordinate to test it.

Solution

1. A horizontal stretch by \(4\) replaces \(x\) with \(\frac{x}{4}\). 2. Reflecting across the x-axis gives \(-\cos\left(\frac{x}{4}\right)\). 3. Shifting right by \(\pi\) gives \(h(x)=-\cos\left(\frac{x-\pi}{4}\right)\). 4. Evaluate: \(h(5\pi)=-\cos\left(\frac{5\pi-\pi}{4}\right)=-\cos(\pi)=1\). Therefore, the point lies on the graph.

Answer

a) \(h(x)=-\cos\left(\frac{x-\pi}{4}\right)\) b) Yes, because \(h(5\pi)=1\).
53230212
The graph shows a sinusoidal function of the form \(f(x)=a\sin(bx)+d\), where \(a>0\) and \(b>0\). Use the graph to find \(a\), \(b\), and \(d\), and write the complete equation. Briefly explain your reasoning.
Figure for problem 532302

Hints

- Average the maximum and minimum values to find the midline. - Find the amplitude as the distance from the midline to an extreme value. - Read one full cycle from the graph, and use \(b=\frac{2\pi}{p}\). - Check a clearly visible point in your equation.

Solution

1. The maximum value is \(1\), and the minimum value is \(-2\). The midline is \(d=\frac{1+(-2)}{2}=-0.5\). 2. The amplitude is \(a=1-(-0.5)=1.5\). 3. The graph returns to the same phase after \(2\) units, so the period is \(2\). Therefore, \(b=\frac{2\pi}{2}=\pi\). 4. The equation is \(f(x)=1.5\sin(\pi x)-0.5\).

Answer

\(a=1.5\), \(b=\pi\), \(d=-0.5\); \(f(x)=1.5\sin(\pi x)-0.5\)
53230312
Graphs a) and b) show periodic functions \(f\) and \(g\). Find a suitable equation of the form \(f(x)=a\sin(bx)\) for graph a) and a suitable equation of the form \(g(x)=a\cos(bx)+d\) for graph b).
Figure for problem 532303

Hints

- Find the period from the distance between corresponding points on consecutive cycles. - Use \(b=\frac{2\pi}{p}\). - Find the midline and amplitude from the maximum and minimum values. - Use the behavior at \(x=0\) to confirm whether the required sine or cosine form fits.

Solution

1. In graph a), the curve passes through \((0, 0)\) while increasing, so the required sine form is appropriate. 2. Its maximum is \(1.5\), so \(a=1.5\). Its period is \(4\), so \(b=\frac{2\pi}{4}=\frac{\pi}{2}\). Thus, \(f(x)=1.5\sin\left(\frac{\pi}{2}x\right)\). 3. In graph b), the maximum is \(2\), and the minimum is \(0\). Therefore, the midline is \(d=1\), and the amplitude is \(a=1\). 4. The distance between consecutive maxima is \(2\), so \(b=\frac{2\pi}{2}=\pi\). Thus, \(g(x)=\cos(\pi x)+1\).

Answer

a) \(f(x)=1.5\sin\left(\frac{\pi}{2}x\right)\) b) \(g(x)=\cos(\pi x)+1\)
53230612
The graph shows two periodic functions, \(f\) and \(g\). Find a suitable equation of the form \(f(x)=a\sin(bx)+d\) for \(f\) and a suitable equation of the form \(g(x)=a\cos(bx)+d\) for \(g\). For each function, determine the midline, amplitude, period, and inside coefficient before writing the equation.
Figure for problem 532306

Hints

- Average the maximum and minimum values to find each midline. - The amplitude is half the distance between the maximum and minimum. - Use the distance between corresponding points on consecutive cycles to find the period. - For the cosine form, decide whether the graph begins at a maximum or a minimum when \(x=0\).

Solution

1. For \(f\), the maximum is \(3\), and the minimum is \(-1\). Thus, the midline is \(d=\frac{3+(-1)}{2}=1\), and the amplitude is \(a=2\). 2. The increasing midline crossings at \(x=0\) and \(x=4\) show that the period is \(4\). Therefore, \(b=\frac{2\pi}{4}=\frac{\pi}{2}\), so \(f(x)=2\sin\left(\frac{\pi}{2}x\right)+1\). 3. For \(g\), the maximum is \(1.5\), and the minimum is \(-1.5\). Thus, the midline is \(d=0\), and the amplitude is \(1.5\). 4. The graph has a minimum at \(x=0\), so the cosine coefficient is negative. Consecutive minima are \(2\) units apart, so \(b=\pi\). Therefore, \(g(x)=-1.5\cos(\pi x)\).

Answer

\(f(x)=2\sin\left(\frac{\pi}{2}x\right)+1\) \(g(x)=-1.5\cos(\pi x)\)
53239212
Figures 1 and 2 show the graphs of trigonometric functions \(g\) and \(h\). Both can be written in the form \(a\sin(b(x-c))+d\). a) For graph \(g\) in Figure 1, find the amplitude, period, inside coefficient, and an equation in the form \(g(x)=a\sin(bx)\). b) For graph \(h\) in Figure 2, find the amplitude, period, inside coefficient, vertical shift, and the smallest positive horizontal shift to the right. Then write an equation in the form \(h(x)=a\sin(b(x-c))+d\).
Figure for problem 532392

Hints

- Use the midline and extrema to find amplitude and vertical shift. - Find the period from corresponding points on consecutive cycles. - Use \(b=\frac{2\pi}{p}\). - An increasing midline crossing identifies the horizontal shift in a positive sine model.

Solution

1. For \(g\), the midline is \(y=0\), and the extrema are \(1.5\) units from the midline, so the amplitude is \(1.5\). 2. One complete cycle has length \(4\), so the period is \(4\), and \(b=\frac{2\pi}{4}=\frac{\pi}{2}\). Thus, \(g(x)=1.5\sin\left(\frac{\pi}{2}x\right)\). 3. For \(h\), the maximum is \(1.5\), and the minimum is \(-0.5\). Thus, the midline is \(d=0.5\), and the amplitude is \(1\). 4. Consecutive minima at \(x=0\) and \(x=4\) show that the period is \(4\), so \(b=\frac{\pi}{2}\). 5. The graph crosses its midline while increasing at \(x=1\), so the smallest positive shift to the right is \(c=1\). Therefore, \(h(x)=\sin\left(\frac{\pi}{2}(x-1)\right)+0.5\).

Answer

a) Amplitude \(1.5\), period \(4\), \(b=\frac{\pi}{2}\); \(g(x)=1.5\sin\left(\frac{\pi}{2}x\right)\) b) Amplitude \(1\), period \(4\), \(b=\frac{\pi}{2}\), \(c=1\), \(d=0.5\); \(h(x)=\sin\left(\frac{\pi}{2}(x-1)\right)+0.5\)
53239412
The graph shows a periodic function of the form \(f(x)=a\cos(bx)\). a) Find the amplitude and period from the graph. Then write the complete equation for \(f(x)\). b) Find the exact coordinates of the marked points \(A\), \(B\), \(C\), and \(D\).
Figure for problem 532394

Hints

- Use the highest and lowest values to find the amplitude. - Find the horizontal distance between consecutive maxima to determine the period. - Use the cosine period formula to find \(b\). - Each x-axis grid interval represents \(\frac{\pi}{2}\). - Substitute each marked x-value into your equation to find its exact y-value.

Solution

1. The graph ranges from \(-2\) to \(2\), so the amplitude is \(a=2\). 2. Consecutive maxima occur at \(x=0\) and \(x=6\pi\), so the period is \(6\pi\). 3. Since \(p=\frac{2\pi}{b}\), \(b=\frac{2\pi}{6\pi}=\frac{1}{3}\). Therefore, \(f(x)=2\cos\left(\frac{x}{3}\right)\). 4. At \(x=-\pi\), \(f(-\pi)=2\cos\left(-\frac{\pi}{3}\right)=1\), so \(A=(-\pi,1)\). 5. At the maximum, \(B=(0,2)\). 6. At the next zero shown, \(C=\left(\frac{3\pi}{2}, 0\right)\). 7. At the minimum, \(D=(3\pi,-2)\).

Answer

a) Amplitude \(2\), period \(6\pi\); \(f(x)=2\cos\left(\frac{x}{3}\right)\) b) \(A=(-\pi,1)\), \(B=(0,2)\), \(C=\left(\frac{3\pi}{2}, 0\right)\), \(D=(3\pi,-2)\)
53239812
The graph shows a sinusoidal function of the form \(f(x)=a\sin(b(x-c))+d\), where \(a>0\) and \(b>0\). a) Find the amplitude \(a\) and vertical shift \(d\). b) Find the period \(p\), and use it to calculate \(b\). c) Find a value of \(c\) with \(0 \leq c < p\), and write the complete equation for \(f\).
Figure for problem 532398

Hints

- Use the highest and lowest points to find the midline and amplitude. - Find the distance between consecutive maxima to determine the period. - Use \(b=\frac{2\pi}{p}\). - Locate an increasing midline crossing to determine \(c\).

Solution

1. The maximum is \(3\), and the minimum is \(-1\). Thus, the midline is \(d=\frac{3+(-1)}{2}=1\), and the amplitude is \(a=2\). 2. Consecutive maxima occur at \(x=2\) and \(x=6\), so the period is \(p=4\). 3. Therefore, \(b=\frac{2\pi}{4}=\frac{\pi}{2}\). 4. The graph crosses the midline while increasing at \(x=1\), so choose \(c=1\), which satisfies \(0 \leq c < 4\). 5. The complete equation is \(f(x)=2\sin\left(\frac{\pi}{2}(x-1)\right)+1\).

Answer

a) \(a=2\), \(d=1\) b) \(p=4\), \(b=\frac{\pi}{2}\) c) \(c=1\); \(f(x)=2\sin\left(\frac{\pi}{2}(x-1)\right)+1\)
53240012
Match each function to graph I, II, or III. Justify each match using characteristics such as amplitude, period, and vertical shift. \(A(x)=\cos(0.5\pi x)+0.5\) \(B(x)=1.5\sin(0.5\pi x)\) \(C(x)=\sin(\pi x)-1\)
Figure for problem 532400

Hints

- Read amplitude, period, and vertical shift from each graph. - An outside constant determines the midline. - The outside coefficient determines the amplitude. - Use the period to identify the coefficient of \(x\). - Check whether the graph starts on the midline or at an extreme value when \(x=0\).

Solution

1. Graph I has midline \(y=-1\), amplitude \(1\), and period \(2\). It crosses the midline at \(x=0\) with positive slope, so it matches \(C(x)=\sin(\pi x)-1\). 2. Graph II has midline \(y=0\), amplitude \(1.5\), and period \(4\). It passes through the origin with positive slope, so it matches \(B(x)=1.5\sin(0.5\pi x)\). 3. Graph III has midline \(y=0.5\), amplitude \(1\), and period \(4\). It begins at a maximum when \(x=0\), so it matches \(A(x)=\cos(0.5\pi x)+0.5\).

Answer

Graph I: \(C(x)\) Graph II: \(B(x)\) Graph III: \(A(x)\)
53240312
The graph shows a function of the form \(f(x)=a\sin(bx)\). Points \(A\), \(B\), \(C\), and \(D\) are marked on the graph. a) Read the coordinates of \(A\), \(B\), \(C\), and \(D\). b) Find the amplitude and period. c) Find \(b\), and write the complete equation for \(f\).
Figure for problem 532403

Hints

- Check the scale on both axes before reading the points. - Identify the maximum, minimum, and x-intercepts. - The amplitude is the greatest distance from the x-axis. - Find the horizontal length of one complete cycle. - Use \(b=\frac{2\pi}{p}\).

Solution

1. The marked points are \(A=(1.5, 1.5)\), \(B=(3, 0)\), \(C=(4.5, -1.5)\), and \(D=(6, 0)\). 2. The maximum distance from the x-axis is \(1.5\), so the amplitude is \(1.5\). 3. The graph begins an increasing cycle at \(x=0\) and returns to the same phase at \(x=6\), so the period is \(6\). 4. Therefore, \(b=\frac{2\pi}{6}=\frac{\pi}{3}\), and \(f(x)=1.5\sin\left(\frac{\pi}{3}x\right)\).

Answer

a) \(A=(1.5, 1.5)\), \(B=(3, 0)\), \(C=(4.5, -1.5)\), \(D=(6, 0)\) b) Amplitude \(1.5\), period \(6\) c) \(b=\frac{\pi}{3}\); \(f(x)=1.5\sin\left(\frac{\pi}{3}x\right)\)
53353012
The graph represents a cosine function of the form \(g(x)=a\cos(bx)\), where \(b>0\). Determine \(a\) and \(b\), and write the complete equation. The x-axis is scaled in multiples of \(\pi\).
Figure for problem 533530

Hints

- Use the y-value at \(x=0\) to check the cosine form and sign of the amplitude. - Measure the distance between consecutive maxima to find the period. - Use \(T=\frac{2\pi}{|b|}\).

Solution

1. The maximum is \(0.5\) and the minimum is \(-0.5\), so the amplitude is \(|a|=0.5\). Because the graph begins at a maximum, \(a=0.5\). 2. Consecutive maxima occur at \(x=0\) and \(x=\pi\), so the period is \(T=\pi\). 3. Since \(T=\frac{2\pi}{|b|}\), \(|b|=\frac{2\pi}{\pi}=2\). Since \(b>0\), \(b=2\), and the equation is \(g(x)=0.5\cos(2x)\).

Answer

\(a=0.5\), \(b=2\), so \(g(x)=0.5\cos(2x)\).
53353212
Find an equation for the graph in the form \(k(x)=a\sin(bx)\). Pay close attention to the sign of \(a\) and to the x-axis scale in multiples of \(\pi\).
Figure for problem 533532

Hints

- Use the direction of the graph at the origin to determine the sign of \(a\). - Find the horizontal length of one complete cycle. - Account for the x-axis scale when calculating \(b\).

Solution

1. The graph ranges from \(-1\) to \(1\), so \(|a|=1\). 2. The graph falls through the origin, so it is a reflection of a positive sine graph across the x-axis. Therefore, \(a=-1\). 3. Consecutive downward x-axis crossings are \(4\pi\) apart, so the period is \(4\pi\). 4. Thus, \(b=\frac{2\pi}{4\pi}=0.5\), and \(k(x)=-\sin(0.5x)\).

Answer

\(k(x)=-\sin(0.5x)\)
53353312
The figure shows two sine graphs. The dashed graph is \(f(x)=\sin(b_f x)\), and the solid graph is \(g(x)=a\sin(b_g x)\). 1. Find the amplitude \(a\) of \(g\). 2. Find the period of each function from the graph. 3. Calculate \(b_f\) and \(b_g\). 4. Describe the transformations from the graph of \(f\) to the graph of \(g\).
Figure for problem 533533

Hints

- Read the amplitude from the highest point. - The period is the horizontal distance over which the pattern first repeats. - Use \(b=\frac{2\pi}{p}\). - Compare both the height and width of the waves.

Solution

1. The maximum value of \(g\) is \(2\), so \(a=2\). 2. The dashed graph completes one cycle in \(6\) units, so \(p_f=6\). The solid graph completes one cycle in \(12\) units, so \(p_g=12\). 3. Use \(b=\frac{2\pi}{p}\): \(b_f=\frac{2\pi}{6}=\frac{\pi}{3}\), and \(b_g=\frac{2\pi}{12}=\frac{\pi}{6}\). 4. The amplitude doubles, giving a vertical stretch by \(2\), and the period doubles, giving a horizontal stretch by \(2\).

Answer

1. \(a=2\) 2. \(p_f=6\); \(p_g=12\) 3. \(b_f=\frac{\pi}{3}\); \(b_g=\frac{\pi}{6}\) 4. Vertical stretch by \(2\) and horizontal stretch by \(2\)
53378212
Match each sine graph with its equation. One equation will not be used. Justify each match by comparing amplitude and period. (1) \(g(x)=2\sin(0.5\pi x)\) (2) \(g(x)=\sin(\pi x)\) (3) \(g(x)=2\sin(\pi x)\) (4) \(g(x)=2\sin(0.25\pi x)\)
Figure for problem 533782

Hints

- Read the amplitude from the greatest distance between each graph and the x-axis. - Find the horizontal length of one complete cycle. - A larger inside coefficient produces a shorter period.

Solution

1. Graph A has amplitude \(2\) and period \(4\). Thus, \(b=\frac{2\pi}{4}=0.5\pi\), so it matches equation (1). 2. Graph B has amplitude \(2\) and period \(2\). Thus, \(b=\pi\), so it matches equation (3). 3. Graph C has amplitude \(1\) and period \(2\). Thus, \(b=\pi\), so it matches equation (2). 4. Equation (4) has amplitude \(2\) and period \(8\), so it is not used.

Answer

A: (1) B: (3) C: (2) Unused: (4)
53382312
Match each function to graph A, B, C, or D. For each one, briefly describe the transformation from \(p(x)=\sin(0.5\pi x)\). 1. \(f(x)=2\sin(0.5\pi x)\) 2. \(g(x)=\sin(0.5\pi x)-1\) 3. \(h(x)=\sin(\pi x)\) 4. \(i(x)=-\sin(0.5\pi x)\)
Figure for problem 533823

Hints

- Compare maximum and minimum values. - Determine the period of each graph. - Check for a vertical shift. - Compare whether the graph initially rises or falls to identify a reflection.

Solution

1. The reference function has amplitude \(1\) and period \(4\). 2. Function \(f\) has amplitude \(2\), so it is graph B, a vertical stretch by \(2\). 3. Function \(g\) has the same shape shifted down \(1\), so it is graph A. 4. Function \(h\) has period \(2\), half the reference period, so it is graph D, a horizontal compression by \(\frac{1}{2}\). 5. Function \(i\) is the reflection of the reference graph across the x-axis, so it is graph C.

Answer

1. B — vertical stretch by \(2\) 2. A — shift down \(1\) 3. D — horizontal compression by \(\frac{1}{2}\) 4. C — reflection across the x-axis
53383312
The graph of \(g\) is obtained from \(f(x)=\sin(x)\) by a vertical compression by a factor of \(0.5\), a horizontal stretch by a factor of \(4\), and a vertical shift up \(1\) unit. Write the equation of \(g\). Which displayed graph—I, II, or III—matches the description? Explain.
Figure for problem 533833

Hints

- Identify the amplitude and vertical shift first. - A horizontal stretch by \(4\) makes the coefficient of \(x\) equal to \(\frac{1}{4}\). - Compare each graph’s midline, amplitude, and period.

Solution

1. The vertical compression gives an amplitude of \(0.5\). A horizontal stretch by \(4\) replaces \(x\) with \(\frac{x}{4}\). The upward shift adds \(1\). Thus, \(g(x)=0.5\sin\left(\frac{x}{4}\right)+1\). 2. Graph II has amplitude \(2\), so it does not match. Graph III has amplitude \(0.5\) and midline \(y=1\), but its period is \(2\pi\). Graph I has amplitude \(0.5\), midline \(y=1\), and period \(8\pi\), so Graph I is correct.

Answer

\(g(x)=0.5\sin\left(\frac{x}{4}\right)+1\) Matching graph: I
53383412
A function \(g\) is obtained from \(f(x)=\cos(x)\) by reflecting across the x-axis, horizontally compressing by a factor of \(0.5\), and shifting down \(2\) units. Write \(g(x)\), and calculate \(g\left(\frac{\pi}{4}\right)\). Use the graph to check your result.
Figure for problem 533834

Hints

- Reflection across the x-axis gives an outside negative sign. - A horizontal compression makes the graph cycle faster. - Substitute \(x=\frac{\pi}{4}\) into the function. - Use the graph as a visual check.

Solution

1. Reflection gives an outside coefficient of \(-1\). 2. A horizontal compression by \(0.5\) gives an inside coefficient of \(2\). 3. Shifting down \(2\) gives \(g(x)=-\cos(2x)-2\). 4. Evaluate: \(g\left(\frac{\pi}{4}\right)=-\cos\left(\frac{\pi}{2}\right)-2=-2\).

Answer

\(g(x)=-\cos(2x)-2\); \(g\left(\frac{\pi}{4}\right)=-2\)
53383712
The graph shows a periodic oscillation. Find \(a\), \(b\), and \(d\) for \(f(x)=a\sin(bx)+d\).
Figure for problem 533837

Hints

- Use the highest and lowest values to find the midline and amplitude. - The distance from a maximum to the next minimum is half a period. - Use \(b=\frac{2\pi}{p}\).

Solution

1. The maximum is \(1.5\), and the minimum is \(0.5\). Thus, the midline is \(d=\frac{1.5+0.5}{2}=1\). 2. The amplitude is \(a=1.5-1=0.5\). 3. The distance from the maximum at \(x=2.5\) to the minimum at \(x=7.5\) is \(5\), which is half a period. Therefore, the period is \(10\). 4. Thus, \(b=\frac{2\pi}{10}=\frac{\pi}{5}\).

Answer

\(a=0.5\), \(b=\frac{\pi}{5}\), \(d=1\)
53384112
Find the amplitude, period, and range of each function. Then compare your results with graphs a) and b). \(f(x)=2\sin(3x)-1\) \(g(x)=0.5\cos(0.5x)+2\)
Figure for problem 533841

Hints

- The amplitude is the absolute value of the coefficient outside the sine or cosine. - Use \(T=\frac{2\pi}{|b|}\) for the period. - Find the lowest and highest values by combining the midline and the amplitude. - Check the midline and one full cycle on each graph.

Solution

1. For \(f(x)=2\sin(3x)-1\), the amplitude is \(|2|=2\). 2. Its period is \(\frac{2\pi}{3}\), because \(T=\frac{2\pi}{|b|}\) and \(b=3\). 3. Its midline is \(y=-1\), so its range is \([-1-2, -1+2]=[-3, 1]\). 4. For \(g(x)=0.5\cos(0.5x)+2\), the amplitude is \(|0.5|=0.5\). 5. Its period is \(\frac{2\pi}{0.5}=4\pi\). 6. Its midline is \(y=2\), so its range is \([2-0.5, 2+0.5]=[1.5, 2.5]\).

Answer

\(f\): amplitude \(2\), period \(\frac{2\pi}{3}\), range \([-3, 1]\) \(g\): amplitude \(0.5\), period \(4\pi\), range \([1.5, 2.5]\)
53384212
A periodic function has the form \(h(x)=a\sin(bx)+d\). Its graph has the following properties: - amplitude \(1.5\) - period \(\pi\) - vertical shift up \(0.5\) unit 1. Write an equation for \(h(x)\). 2. Find the range of the function. 3. Verify your equation using the graph.
Figure for problem 533842

Hints

- Match the amplitude and vertical shift to \(a\) and \(d\). - Use the period formula to determine \(b\). - The range extends one amplitude below and above the midline. - Check the extrema, midline, and distance between corresponding points on consecutive cycles.

Solution

1. The amplitude gives \(a=1.5\), and the vertical shift gives \(d=0.5\). 2. Since \(T=\frac{2\pi}{|b|}\), the condition \(T=\pi\) gives \(|b|=2\). Taking \(b=2\), an equation is \(h(x)=1.5\sin(2x)+0.5\). 3. The minimum is \(0.5-1.5=-1\), and the maximum is \(0.5+1.5=2\). Therefore, the range is \([-1, 2]\). 4. The graph oscillates about \(y=0.5\), reaches \(-1\) and \(2\), and repeats every \(\pi\), confirming the equation.

Answer

1. \(h(x)=1.5\sin(2x)+0.5\) 2. \([-1, 2]\) 3. The graph has midline \(y=0.5\), extrema \(-1\) and \(2\), and period \(\pi\).
53384412
The graph shows two functions, \(p\) and \(q\). 1. Which graph has the greater amplitude? 2. Which graph has the higher frequency, or shorter period? 3. Find an equation for \(p\) in the form \(p(x)=a\sin(bx)+d\).
Figure for problem 533844

Hints

- The amplitude is the greatest distance from the midline. - A graph with a shorter period has a higher frequency. - For \(p\), find the period and check whether the graph crosses the midline at \(x=0\).

Solution

1. Graph \(p\) has amplitude \(1.5\). Graph \(q\) oscillates about \(y=2\) from \(1\) to \(3\), so its amplitude is \(1\). Therefore, \(p\) has the greater amplitude. 2. Graph \(p\) has period \(2\pi\), while graph \(q\) has period \(\pi\). Therefore, \(q\) has the higher frequency. 3. For \(p\), the midline is \(y=0\), the amplitude is \(1.5\), and \(b=\frac{2\pi}{2\pi}=1\). Thus, \(p(x)=1.5\sin(x)\).

Answer

1. Graph \(p\) 2. Graph \(q\) 3. \(p(x)=1.5\sin(x)\)
53385412
The graph shows \(g(x)=2\cos\left(\frac{\pi}{4}x\right)\). a) Find the amplitude and period of \(g\). b) Give the coordinates of the labeled points \(P\), \(Q\), and \(R\).
Figure for problem 533854

Hints

- Read the amplitude from the greatest distance from the x-axis. - The period is the horizontal distance between consecutive maximum points. - Substitute the marked x-values to confirm the y-coordinates. - Pay attention to the scale on each axis.

Solution

1. The coefficient outside cosine is \(2\), so the amplitude is \(2\). 2. The coefficient of \(x\) is \(b=\frac{\pi}{4}\). Thus, the period is \(p=\frac{2\pi}{\pi/4}=8\). 3. \(g(0)=2\cos(0)=2\), so \(P(0, 2)\). 4. \(g(2)=2\cos\left(\frac{\pi}{2}\right)=0\), so \(Q(2, 0)\). 5. \(g(4)=2\cos(\pi)=-2\), so \(R(4, -2)\).

Answer

a) Amplitude: \(2\); period: \(8\) b) \(P(0, 2)\), \(Q(2, 0)\), \(R(4, -2)\)
53386112
Find an equation for the graph in the form \(f(x)=a\sin(b(x-c))+d\). Then determine whether the same graph can be represented by a cosine equation of the form \(g(x)=a\cos(b(x-c'))+d\).
Figure for problem 533861

Hints

- Average the maximum and minimum to find the midline. - Find the period from the distance between maxima. - Use an increasing midline crossing for the sine form. - Use a maximum for the cosine form.

Solution

1. The maximum is \(2.5\), and the minimum is \(-0.5\). Thus, the midline is \(d=\frac{2.5+(-0.5)}{2}=1\), and the amplitude is \(a=1.5\). 2. Consecutive maxima occur at \(x=1\) and \(x=5\), so the period is \(4\), and \(b=\frac{2\pi}{4}=\frac{\pi}{2}\). 3. The graph crosses the midline while increasing at \(x=0\), so a sine equation is \(f(x)=1.5\sin\left(\frac{\pi}{2}x\right)+1\). 4. The graph has a maximum at \(x=1\), so a cosine equation is \(g(x)=1.5\cos\left(\frac{\pi}{2}(x-1)\right)+1\).

Answer

Sine form: \(f(x)=1.5\sin\left(\frac{\pi}{2}x\right)+1\) Cosine form: \(g(x)=1.5\cos\left(\frac{\pi}{2}(x-1)\right)+1\)
53386212
The graph describes a periodic process. Find an equation in the form \(f(x)=a\sin(b(x-c))+d\). Determine the horizontal shift precisely.
Figure for problem 533862

Hints

- Use the grid carefully to identify fractional horizontal shifts. - Each x-axis grid interval represents \(0.25\) unit. - The period is the horizontal length of one complete cycle.

Solution

1. The maximum is \(1\), and the minimum is \(-3\). Thus, the midline is \(d=-1\), and the amplitude is \(a=2\). 2. Increasing midline crossings occur at \(x=0.25\) and \(x=2.25\), so the period is \(2\). 3. Therefore, \(b=\frac{2\pi}{2}=\pi\). 4. The increasing midline crossing at \(x=0.25\) gives \(c=0.25\). 5. Thus, \(f(x)=2\sin\left(\pi\left(x-\frac{1}{4}\right)\right)-1\).

Answer

\(f(x)=2\sin\left(\pi\left(x-\frac{1}{4}\right)\right)-1\)
53387012
The graph of \(g\) was obtained from the graph of \(f(x)=\cos(x)\) by a vertical compression, a horizontal shift, and a vertical shift. Describe the transformations and write an equation for \(g(x)\).
Figure for problem 533870

Hints

- Use the graph's midline to determine the vertical shift. - Use the distance from the midline to a maximum to determine the amplitude. - Compare the location of a maximum with the maximum of \(\cos(x)\) at \(x=0\).

Solution

1. The graph has midline \(y=1\), so the cosine graph is shifted up \(1\) unit. 2. The amplitude is \(0.5\), so the graph is vertically compressed by a factor of \(0.5\). 3. A maximum occurs at \(x=\frac{\pi}{2}\) instead of at \(x=0\), so the graph is shifted right \(\frac{\pi}{2}\). 4. Therefore, \(g(x)=0.5\cos\left(x-\frac{\pi}{2}\right)+1\). Equivalently, \(g(x)=0.5\sin(x)+1\).

Answer

Vertically compress by a factor of \(0.5\), shift right \(\frac{\pi}{2}\), and shift up \(1\). One equation is \(g(x)=0.5\cos\left(x-\frac{\pi}{2}\right)+1\).
53387912
The parent function is \(f(x)=\sin(x)\). The graph also shows the transformed function \(g(x)=2\sin\left(\frac{\pi}{2}(x-1)\right)+1\). Describe, step by step, the transformations that produce the graph of \(g\) from the graph of \(f\).
Figure for problem 533879

Hints

- Examine the outside coefficient, the coefficient inside the sine, the expression in parentheses, and the final constant separately. - Decide whether each parameter causes a stretch, compression, reflection, or shift. - Use the amplitude and period formulas. - Pay close attention to the sign in \(x-1\).

Solution

1. The outside coefficient \(2\) vertically stretches the graph by a factor of \(2\), so the amplitude is \(2\). 2. The inside coefficient is \(\frac{\pi}{2}\), so the period is \(\frac{2\pi}{\pi/2}=4\). This is a horizontal compression by a factor of \(\frac{2}{\pi}\). 3. The expression \(x-1\) shifts the graph right \(1\) unit. 4. The final \(+1\) shifts the graph up \(1\) unit.

Answer

Vertically stretch by a factor of \(2\), horizontally compress by a factor of \(\frac{2}{\pi}\), shift right \(1\) unit, and shift up \(1\) unit.
53388012
The graph of \(f(x)=\cos(x)\) is transformed to produce \(g(x)=-0.5\cos(\pi x)-2\). Explain the geometric effect of each parameter. Use the graph to check your description.
Figure for problem 533880

Hints

- Determine the effects of the sign and magnitude of the outside coefficient separately. - Use the inside coefficient to find the new period. - Compare the new midline with the x-axis. - Check each change against the two graphs.

Solution

1. The outside coefficient \(-0.5\) reflects the graph across the x-axis and vertically compresses it by a factor of \(0.5\). The amplitude is \(0.5\). 2. The inside coefficient \(\pi\) changes the period to \(T=\frac{2\pi}{\pi}=2\). This is a horizontal compression by a factor of \(\frac{1}{\pi}\). 3. The final \(-2\) shifts the graph down \(2\) units.

Answer

Reflect across the x-axis, vertically compress by a factor of \(0.5\), horizontally compress by a factor of \(\frac{1}{\pi}\), and shift down \(2\) units.
53404112
The graph shows the parent function \(f(x)=\sin(x)\) as a dashed curve and two transformed graphs, \(g\) and \(h\). Find equations for \(g(x)\) and \(h(x)\).
Figure for problem 534041

Hints

- Find each amplitude from half the distance between the maximum and minimum. - Identify each midline. - Use the period to calculate the inside coefficient. - Locate an increasing midline crossing to determine a horizontal shift.

Solution

1. Graph \(g\) has amplitude \(2\), no vertical shift, and period \(4\pi\). Thus, \(b=\frac{2\pi}{4\pi}=0.5\), so \(g(x)=2\sin(0.5x)\). 2. Graph \(h\) has amplitude \(1\), midline \(y=1\), and period \(2\pi\). It crosses the midline while increasing at \(x=\frac{\pi}{2}\), so it is shifted right \(\frac{\pi}{2}\). 3. Therefore, \(h(x)=\sin\left(x-\frac{\pi}{2}\right)+1\).

Answer

\(g(x)=2\sin(0.5x)\) \(h(x)=\sin\left(x-\frac{\pi}{2}\right)+1\)
53406912
The red graph \(g\) is a transformation of the blue graph \(f(x)=\sin\left(\frac{\pi}{2}x\right)\). Determine a function rule for \(g\).
Figure for problem 534069

Hints

- Compare the amplitudes of the two graphs. - Identify each midline. - Compare the x-coordinates of corresponding maximum points.

Solution

1. The amplitude of \(f\) is \(1\), while the amplitude of \(g\) is \(2\). Therefore, the graph is stretched vertically by a factor of \(2\). 2. The midline moves from \(y=0\) to \(y=1\), so the graph shifts up \(1\) unit. 3. A maximum of \(f\) occurs at \((1, 1)\), while the corresponding maximum of \(g\) occurs at \((2, 3)\). Therefore, the graph shifts right \(1\) unit. 4. Thus, \(g(x)=2f(x-1)+1=2\sin\left(\frac{\pi}{2}(x-1)\right)+1\).

Answer

\(g(x)=2\sin\left(\frac{\pi}{2}(x-1)\right)+1\)
53409312
The blue graph is \(f(x)=\cos x\), and the red graph is a periodic function \(g\). Describe the horizontal transformation and write \(g(x)\) in terms of \(f(x)\).
Figure for problem 534093

Hints

- Compare the distances between consecutive maximum points. - Determine how the periods of the two graphs are related. - A larger coefficient on \(x\) produces a shorter period.

Solution

1. The period of \(f\) is \(2\pi\), while the period of \(g\) is \(\pi\). 2. The period is halved, so the graph is horizontally compressed by a factor of \(\frac{1}{2}\). 3. Replacing \(x\) with \(2x\) produces this compression. Therefore, \(g(x)=f(2x)\).

Answer

Horizontal compression by a factor of \(\frac{1}{2}\); \(g(x)=f(2x)\)
53440612
The figure shows graphs from the family \(g_k(x)=\sin(kx)\) for \(x\ge0\). Find the value of \(k\) for graphs p, q, and r.
Figure for problem 534406

Hints

- Use the relationship between \(k\) and the period. - Compare where each graph completes one full cycle. - Zeros can help identify half of a period.

Solution

1. The period of \(\sin(kx)\) is \(P=\frac{2\pi}{k}\). 2. Graph p has period \(2\pi\), so \(k=1\). 3. Graph q has period \(\pi\), so \(k=2\). 4. Graph r has period \(4\pi\), so \(k=0.5\).

Answer

p) \(k=1\) q) \(k=2\) r) \(k=0.5\)
53441712
Consider the family \(f_k(x)=\sin(kx)\), where \(k>0\). The graph shows curves I, II, and III for three values of \(k\). a) What do all graphs in this family have in common at \((0, 0)\)? b) Match \(k=0.5\), \(k=1\), and \(k=2\) to graphs I, II, and III. Explain. c) Describe what happens to the period when \(k\) is doubled. d) Find the smallest positive zero when \(k=1.5\). Give an exact answer in terms of \(\pi\).
Figure for problem 534417

Hints

- Compare how many cycles each graph completes over a fixed interval. - Use the period formula \(\frac{2\pi}{k}\). - The first positive zero of the standard sine function occurs when its input is \(\pi\).

Solution

1. Every graph passes through \((0, 0)\) because \(\sin(k\cdot 0)=0\). 2. A larger \(k\) gives a shorter period. Graph I varies most slowly, so \(k=0.5\). Graph II is the standard sine graph, so \(k=1\). Graph III varies most rapidly, so \(k=2\). 3. The period is \(\frac{2\pi}{k}\). Doubling \(k\) halves the period. 4. For the smallest positive zero, \(1.5x=\pi\), so \(x=\frac{2\pi}{3}\).

Answer

a) All pass through \((0, 0)\). b) I: \(k=0.5\); II: \(k=1\); III: \(k=2\) c) The period is halved. d) \(x=\frac{2\pi}{3}\)
52373912
Consider the functions \(h(x)=1.5\sin(3x-\pi)\) and \(k(x)=1.5\sin(3(x-\pi))\). 1. Find the amplitude and period of both functions. 2. Describe one horizontal shift from \(p(x)=1.5\sin(3x)\) to each graph. 3. Compare the actual locations of the graphs. Is either graph truly farther to the right?

Hints

- Interpret the parameters in \(a\sin(b(x-c))\). - Factor the coefficient of \(x\) before reading the horizontal shift. - Relate the inside coefficient to the period. - Shifts that differ by a whole period produce the same graph.

Solution

1. Both functions have amplitude \(1.5\) and period \(T=\frac{2\pi}{3}\). 2. Rewrite \(h(x)=1.5\sin\left(3\left(x-\frac{\pi}{3}\right)\right)\), so one shift is \(\frac{\pi}{3}\) right. The form of \(k\) displays a shift of \(\pi\) right. 3. The displayed shifts differ by \(\pi-\frac{\pi}{3}=\frac{2\pi}{3}\), exactly one period. Also, \(k(x)=1.5\sin(3x-3\pi)=1.5\sin(3x-\pi-2\pi)=h(x)\). Therefore, the graphs are identical.

Answer

1. Amplitude: \(1.5\); period: \(\frac{2\pi}{3}\) 2. \(h\): shift right \(\frac{\pi}{3}\); \(k\): shift right \(\pi\) 3. The graphs are identical because the shifts differ by one full period. Neither graph is actually farther right.
52374012
Consider \(f(x)=2\sin\left(\frac{1}{2}x-\frac{\pi}{4}\right)\) and \(g(x)=2\sin\left(\frac{1}{2}\left(x-\frac{\pi}{4}\right)\right)\). Find the first maximum point of each graph for \(x>0\). Which graph reaches its first maximum at the smaller x-value? Justify your answer.

Hints

- Recall the input where the parent sine function first reaches its maximum. - Set the entire sine input equal to that value. - Solve each equation for \(x\). - Compare the two x-coordinates.

Solution

1. A sine function reaches a maximum when its input is \(\frac{\pi}{2}+2\pi k\). 2. For \(f\), solve \(\frac{1}{2}x-\frac{\pi}{4}=\frac{\pi}{2}\). This gives \(x=\frac{3\pi}{2}\). 3. For \(g\), solve \(\frac{1}{2}\left(x-\frac{\pi}{4}\right)=\frac{\pi}{2}\). This gives \(x=\frac{5\pi}{4}\). 4. Since \(\frac{5\pi}{4}<\frac{3\pi}{2}\), \(g\) reaches its first maximum earlier. Both maximum values are \(2\).

Answer

\(f\) has its first maximum at \(\left(\frac{3\pi}{2}, 2\right)\). \(g\) has its first maximum at \(\left(\frac{5\pi}{4}, 2\right)\). The graph of \(g\) reaches its first maximum earlier.

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