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Hyperbolas and their asymptotes

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54382612
For the hyperbola \(\frac{(x+1)^2}{49}-\frac{(y-3)^2}{16}=1\), state the center, vertices, and equations of both asymptotes.

Hints

- Read the center from the horizontal and vertical shifts. - The positive squared term gives the transverse-axis direction. - For a horizontal hyperbola, the asymptote slope magnitude is \(\frac{b}{a}\).

Solution

1. The center is \((-1, 3)\). 2. The positive x-term shows that the transverse axis is horizontal. Since \(a=7\), the vertices are \((-8, 3)\) and \((6, 3)\). 3. Here \(b=4\), so the asymptote slope magnitude is \(\frac{b}{a}=\frac{4}{7}\). 4. The asymptotes are \(y-3=\frac{4}{7}(x+1)\) and \(y-3=-\frac{4}{7}(x+1)\).

Answer

Center: \((-1, 3)\) Vertices: \((-8, 3)\), \((6, 3)\) Asymptotes: \(y-3=\frac{4}{7}(x+1)\) and \(y-3=-\frac{4}{7}(x+1)\)
54383312
For the hyperbola \(\frac{(y-1)^2}{25}-\frac{(x+2)^2}{9}=1\), state its center, vertices, and equations of both asymptotes.

Hints

- Read the center from the shifts in standard form. - The positive squared term identifies the transverse-axis direction. - For a vertical hyperbola, the asymptote slope magnitude is \(\frac{a}{b}\).

Solution

1. The center is \((-2, 1)\). 2. The positive y-term shows that the transverse axis is vertical. Since \(a=5\), the vertices are \((-2, 6)\) and \((-2, -4)\). 3. Here \(b=3\), so the asymptote slope magnitude for a vertical hyperbola is \(\frac{a}{b}=\frac{5}{3}\). 4. The asymptotes are \(y-1=\frac{5}{3}(x+2)\) and \(y-1=-\frac{5}{3}(x+2)\).

Answer

Center: \((-2, 1)\) Vertices: \((-2, 6)\), \((-2, -4)\) Asymptotes: \(y-1=\frac{5}{3}(x+2)\) and \(y-1=-\frac{5}{3}(x+2)\)
54375112
For the hyperbola \(H:\frac{x^2}{25}-\frac{y^2}{4}=1\): a) Write the equation of its conjugate hyperbola. b) State the vertices of both hyperbolas and their common asymptotes. c) Determine whether the two hyperbolas intersect.

Hints

- A conjugate hyperbola reverses which squared term is positive. - Compare the guide rectangles of the two standard forms. - Test possible common points by combining the two equations.

Solution

1. Interchanging the positive and negative squared terms gives the conjugate hyperbola \(\frac{y^2}{4}-\frac{x^2}{25}=1\). 2. The vertices of \(H\) are \((\pm5, 0)\). The vertices of the conjugate hyperbola are \((0, \pm2)\). 3. Both hyperbolas use the same asymptote rectangle, so their asymptotes are \(y=\pm\frac{2}{5}x\). 4. If a point satisfied both equations, adding them would give \(0=2\), which is impossible. 5. Therefore the two conjugate hyperbolas do not intersect.

Answer

a) \(\frac{y^2}{4}-\frac{x^2}{25}=1\) b) Vertices of \(H\): \((\pm5, 0)\); vertices of the conjugate: \((0, \pm2)\); asymptotes: \(y=\pm\frac{2}{5}x\) c) They do not intersect.
54379812
The graph shows a horizontal hyperbola centered at the origin. The marked vertices lie on the x-axis, and the marked point \(A\) lies on the upper-right asymptote. Use the graph to write the hyperbola in standard form and state both asymptotes.
Figure for problem 543798

Hints

- Read \(a\) from the center-to-vertex distance. - Use the marked point to determine the slope of the upper-right asymptote. - For a horizontal hyperbola, the asymptote slope magnitude is \(\frac{b}{a}\).

Solution

1. The vertices are \((\pm3, 0)\), so \(a=3\) and \(a^2=9\). 2. The upper-right asymptote passes through the origin and \(A=(3, 2)\), so its slope is \(\frac{2}{3}\). 3. For a horizontal hyperbola, the asymptote slope is \(\frac{b}{a}\). Thus \(\frac{b}{3}=\frac{2}{3}\), so \(b=2\) and \(b^2=4\). 4. The standard form is \(\frac{x^2}{9}-\frac{y^2}{4}=1\). 5. The asymptotes are \(y=\frac{2}{3}x\) and \(y=-\frac{2}{3}x\).

Answer

Standard form: \(\frac{x^2}{9}-\frac{y^2}{4}=1\) Asymptotes: \(y=\frac{2}{3}x\) and \(y=-\frac{2}{3}x\)
54381912
A hyperbola is centered at \((2, -3)\), has a vertical transverse axis, vertices \((2, 1)\) and \((2, -7)\), and asymptotes \(y+3=\pm2(x-2)\). Write the hyperbola in standard form.

Hints

- Use the center and vertices to determine \(a\). - For a vertical hyperbola, the asymptote slope magnitude is \(\frac{a}{b}\). - Place the positive term under the variable aligned with the transverse axis.

Solution

1. The center-to-vertex distance is \(a=4\), so \(a^2=16\). 2. For a vertical hyperbola, the asymptote slope magnitude is \(\frac{a}{b}\). 3. Since \(\frac{a}{b}=2\) and \(a=4\), it follows that \(b=2\), so \(b^2=4\). 4. The standard form is \(\frac{(y+3)^2}{16}-\frac{(x-2)^2}{4}=1\).

Answer

\(\frac{(y+3)^2}{16}-\frac{(x-2)^2}{4}=1\)
54383912
Identify the conic represented by \(25x^2-16y^2-200x-64y-64=0\). Write it in standard form and state its center, vertices, and asymptotes.

Hints

- Keep the negative sign attached to the complete y-group while completing the square. - The positive squared term identifies the transverse-axis direction. - Use the square roots of the denominators to form the asymptote slopes.

Solution

1. Group the variable terms: \(25(x^2-8x)-16(y^2+4y)-64=0\). 2. Complete both squares: \(25((x-4)^2-16)-16((y+2)^2-4)-64=0\). 3. Simplify to \(25(x-4)^2-16(y+2)^2=400\). 4. Divide by \(400\): \(\frac{(x-4)^2}{16}-\frac{(y+2)^2}{25}=1\). 5. The graph is a horizontal hyperbola centered at \((4, -2)\), with vertices \((0, -2)\) and \((8, -2)\). 6. Its asymptotes are \(y+2=\pm\frac{5}{4}(x-4)\).

Answer

The conic is a horizontal hyperbola with standard form \(\frac{(x-4)^2}{16}-\frac{(y+2)^2}{25}=1\). Center: \((4, -2)\) Vertices: \((0, -2)\), \((8, -2)\) Asymptotes: \(y+2=\pm\frac{5}{4}(x-4)\)
54384612
A hyperbola has center \((3, 1)\), horizontal vertices \((-2, 1)\) and \((8, 1)\), and asymptotes \(y-1=\pm\frac{3}{5}(x-3)\). Write its equation in standard form.

Hints

- Use the center-to-vertex distance to determine \(a\). - For a horizontal hyperbola, compare each asymptote slope with \(\pm\frac{b}{a}\). - Translate the horizontal-hyperbola standard form to the given center.

Solution

1. The vertices are \(5\) units to the left and right of the center, so \(a=5\). 2. For a horizontal hyperbola, the asymptotes have slopes \(\pm\frac{b}{a}\). 3. Since the given slopes are \(\pm\frac{3}{5}\), \(b=3\). 4. The standard form is \(\frac{(x-h)^2}{a^2}-\frac{(y-k)^2}{b^2}=1\). 5. Substituting \((h,k)=(3,1)\), \(a=5\), and \(b=3\) gives \(\frac{(x-3)^2}{25}-\frac{(y-1)^2}{9}=1\).

Answer

\(\frac{(x-3)^2}{25}-\frac{(y-1)^2}{9}=1\)
54387312
A hyperbola is centered at the origin, has foci \((\pm13,0)\), and has asymptotes \(y=\pm\frac{12}{5}x\). Write its equation in standard form and state its vertices.

Hints

- The focus locations determine the transverse-axis direction and the value of \(c\). - For a horizontal hyperbola, the asymptote slopes are \(\pm\frac{b}{a}\). - Use the hyperbola relation \(c^2=a^2+b^2\), which differs from the ellipse relation.

Solution

1. The foci lie on the x-axis, so the hyperbola opens left and right and has form \(\frac{x^2}{a^2}-\frac{y^2}{b^2}=1\). 2. The focal distance is \(c=13\), and the asymptote slopes give \(\frac{b}{a}=\frac{12}{5}\). 3. Write \(a=5k\) and \(b=12k\). 4. For a hyperbola, \(c^2=a^2+b^2\), so \(169=25k^2+144k^2=169k^2\). 5. Since lengths are positive, \(k=1\), giving \(a=5\) and \(b=12\). 6. The equation is \(\frac{x^2}{25}-\frac{y^2}{144}=1\), and the vertices are \((\pm5,0)\).

Answer

Equation: \(\frac{x^2}{25}-\frac{y^2}{144}=1\) Vertices: \((-5, 0)\) and \((5, 0)\)
54390112
A hyperbola has center \((-3,4)\), horizontal vertices \((-8,4)\) and \((2,4)\), and foci \((-16,4)\) and \((10,4)\). Write its equation in standard form and state its asymptotes.

Hints

- Read \(a\) from the center-to-vertex distance and \(c\) from the center-to-focus distance. - For a hyperbola, use \(c^2=a^2+b^2\), not the ellipse relation. - Translate the asymptotes \(y=\pm\frac{b}{a}x\) to the given center.

Solution

1. The center-to-vertex distance is \(a=5\), and the center-to-focus distance is \(c=13\). 2. For a hyperbola, \(c^2=a^2+b^2\), so \(b^2=169-25=144\). 3. A horizontal hyperbola centered at \((h,k)\) has equation \(\frac{(x-h)^2}{a^2}-\frac{(y-k)^2}{b^2}=1\). 4. Therefore, the equation is \(\frac{(x+3)^2}{25}-\frac{(y-4)^2}{144}=1\). 5. Its asymptotes are \(y-4=\pm\frac{12}{5}(x+3)\).

Answer

Equation: \(\frac{(x+3)^2}{25}-\frac{(y-4)^2}{144}=1\) Asymptotes: \(y-4=\pm\frac{12}{5}(x+3)\)
54390812
The hyperbola \(\frac{x^2}{49}-\frac{y^2}{576}=1\) has foci \(F_1\) and \(F_2\). Find every point \(P\) on the hyperbola for which triangle \(F_1PF_2\) has area \(600\) square units.

Hints

- Use the segment between the foci as the triangle's base. - The perpendicular height to that horizontal base is \(|y|\). - Substitute the resulting y-coordinate into the hyperbola and include all sign combinations.

Solution

1. The focal distance is \(c=\sqrt{49+576}=25\), so the foci are \((-25,0)\) and \((25,0)\). 2. The focal segment has length \(50\). Using it as the triangle base, the area is \(\frac{1}{2}(50)|y|=25|y|\). 3. Setting \(25|y|=600\) gives \(|y|=24\). 4. Substitute \(y^2=576\) into the hyperbola: \(\frac{x^2}{49}-1=1\). 5. Thus, \(x^2=98\), so \(x=\pm7\sqrt{2}\). 6. Both signs of \(x\) and both signs of \(y\) are possible.

Answer

The four points are \((7\sqrt{2}, 24)\), \((7\sqrt{2}, -24)\), \((-7\sqrt{2}, 24)\), and \((-7\sqrt{2}, -24)\).
54391512
A rectangular hyperbola has asymptotes \(x=1\) and \(y=-2\), and it passes through \((4,0)\). Write its equation, state its center, and identify which two regions determined by the asymptotes contain its branches.

Hints

- Translate the coordinates so the two asymptotes become the coordinate axes. - Use the product form \(UV=k\) and substitute the known point to determine \(k\). - The sign of \(k\) determines whether the shifted coordinates have matching or opposite signs on the branches.

Solution

1. Shift to \(U=x-1\) and \(V=y+2\), so the asymptotes become \(U=0\) and \(V=0\). 2. A rectangular hyperbola with these asymptotes has equation \(UV=k\). 3. The point \((4,0)\) gives \(U=3\) and \(V=2\), so \(k=6\). 4. Therefore, the equation is \((x-1)(y+2)=6\). 5. The center is the intersection of the asymptotes, \((1,-2)\). 6. Since the product is positive, the branches lie where \(x-1\) and \(y+2\) have the same sign: upper right and lower left relative to the center.

Answer

Equation: \((x-1)(y+2)=6\) Center: \((1, -2)\) Branches: upper right and lower left relative to the center
54392212
For the hyperbola \(\frac{x^2}{144}-\frac{y^2}{25}=1\), let \(L_R\) and \(L_L\) be its right and left directrices. For a point \(P\) on the hyperbola, let \(d_R\) and \(d_L\) be the distances from \(P\) to those directrices. Prove that \(d_L-d_R\) is constant on each branch, and use its sign to distinguish the branches.

Hints

- Find \(c\), eccentricity, and the two directrix locations from the standard equation. - Remove the absolute values separately for points on the right and left branches. - Compare the simplified distance differences and interpret their signs.

Solution

1. Here \(a=12\), \(b=5\), and \(c=\sqrt{144+25}=13\), so \(e=\frac{13}{12}\). 2. The directrices are \(x=\pm\frac{a}{e}=\pm\frac{144}{13}\). 3. On the right branch, \(x\ge12\). Thus, \(d_L=x+\frac{144}{13}\) and \(d_R=x-\frac{144}{13}\), so \(d_L-d_R=\frac{288}{13}\). 4. On the left branch, \(x\le-12\). Thus, \(d_L=-x-\frac{144}{13}\) and \(d_R=-x+\frac{144}{13}\), so \(d_L-d_R=-\frac{288}{13}\). 5. Therefore, the sign of the constant difference identifies the branch.

Answer

Right branch: \(d_L-d_R=\frac{288}{13}\) Left branch: \(d_L-d_R=-\frac{288}{13}\) A positive difference identifies the right branch, and a negative difference identifies the left branch.
54392912
A hyperbola has center \((2,-1)\), vertical vertices \((2,4)\) and \((2,-6)\), and asymptotes \(y+1=\pm\frac{5}{4}(x-2)\). Write its equation in standard form and state its foci.

Hints

- Use the center-to-vertex distance to determine \(a\). - For a vertical hyperbola, compare the asymptote slopes with \(\pm\frac{a}{b}\). - Use \(c^2=a^2+b^2\) and place the foci along the vertical transverse axis.

Solution

1. The center-to-vertex distance is \(a=5\). 2. For a vertical hyperbola, the asymptote slopes are \(\pm\frac{a}{b}\). 3. Since \(\frac{a}{b}=\frac{5}{4}\), \(b=4\). 4. The equation is \(\frac{(y+1)^2}{25}-\frac{(x-2)^2}{16}=1\). 5. For a hyperbola, \(c^2=a^2+b^2=25+16=41\), so \(c=\sqrt{41}\). 6. The foci are \((2,-1\pm\sqrt{41})\).

Answer

Equation: \(\frac{(y+1)^2}{25}-\frac{(x-2)^2}{16}=1\) Foci: \((2, -1-\sqrt{41})\) and \((2, -1+\sqrt{41})\)
54393612
Consider the conjugate hyperbolas \(H_1:\frac{x^2}{9}-\frac{y^2}{4}=1\) and \(H_2:\frac{y^2}{4}-\frac{x^2}{9}=1\). a) Find the asymptotes of each hyperbola. b) Determine whether the two hyperbolas have any finite intersection points. c) Explain their geometric relationship.

Hints

- Read each asymptote slope from the ratio of the two semi-axis parameters. - Compare the two left-hand expressions before solving a system. - Conjugate hyperbolas exchange which squared term is positive while retaining the same asymptotes.

Solution

1. For \(H_1\), setting the right side informally to zero in the translated homogeneous part gives asymptotes \(y=\pm\frac{2}{3}x\). 2. Reversing the positive and negative squared terms for \(H_2\) produces the same two asymptote lines. 3. The left side of the equation for \(H_2\) is the negative of the left side for \(H_1\). 4. A common point would require one expression to equal both \(1\) and \(-1\), which is impossible. 5. Thus, the hyperbolas do not intersect. They share a center and asymptotes, and their transverse axes are perpendicular.

Answer

a) Both hyperbolas have asymptotes \(y=\pm\frac{2}{3}x\). b) They have no finite intersection points. c) They are conjugate hyperbolas with the same center and asymptotes and perpendicular transverse axes.
54395812
A vertical hyperbola is centered at \((0, 5)\). Its vertices are \((0, 1)\) and \((0, 9)\), and its asymptotes are \(y-5=\pm\frac23x\). Write the hyperbola in standard form and find its foci.

Hints

- Use the vertex distance from the center to determine \(a\). - For a vertical hyperbola, the asymptote slopes are \(\pm\frac{a}{b}\). - Use the hyperbola relationship \(c^2=a^2+b^2\) to locate the foci.

Solution

1. The vertices are \(4\) units above and below the center, so \(a=4\) and \(a^2=16\). 2. For a vertical hyperbola, the asymptotes have slopes \(\pm\frac{a}{b}\). 3. Since \(\frac{a}{b}=\frac23\), \(\frac{4}{b}=\frac23\), so \(b=6\) and \(b^2=36\). 4. The standard equation is \(\frac{(y-5)^2}{16}-\frac{x^2}{36}=1\). 5. For a hyperbola, \(c^2=a^2+b^2=16+36=52\), so \(c=2\sqrt{13}\). 6. The foci lie on the vertical transverse axis at \((0, 5\pm2\sqrt{13})\).

Answer

Equation: \(\frac{(y-5)^2}{16}-\frac{x^2}{36}=1\) Foci: \((0, 5+2\sqrt{13})\) and \((0, 5-2\sqrt{13})\)
54396412
A horizontal hyperbola is centered at \((2, -1)\). One vertex is \((8, -1)\), and its asymptotes are \(y+1=\pm\frac56(x-2)\). Write the hyperbola in standard form and state its other vertex and foci.

Hints

- Use the center-to-vertex distance to determine the transverse semi-axis. - For a horizontal hyperbola, compare the asymptote slopes with \(\pm\frac{b}{a}\). - Use \(c^2=a^2+b^2\) after finding both denominators.

Solution

1. The distance from the center \((2, -1)\) to the vertex \((8, -1)\) is \(a=6\), so \(a^2=36\). 2. For a horizontal hyperbola, the asymptote slopes are \(\pm\frac{b}{a}\). 3. Since \(\frac{b}{a}=\frac56\) and \(a=6\), it follows that \(b=5\) and \(b^2=25\). 4. The standard equation is \(\frac{(x-2)^2}{36}-\frac{(y+1)^2}{25}=1\). 5. The other vertex is \((2-6, -1)=(-4, -1)\). 6. For a hyperbola, \(c^2=a^2+b^2=36+25=61\), so \(c=\sqrt{61}\). 7. The foci are \((2\pm\sqrt{61}, -1)\).

Answer

Equation: \(\frac{(x-2)^2}{36}-\frac{(y+1)^2}{25}=1\) Other vertex: \((-4, -1)\) Foci: \((2+\sqrt{61}, -1)\) and \((2-\sqrt{61}, -1)\)
54397012
For the hyperbola \(\frac{x^2}{16}-\frac{y^2}{20}=1\), find the endpoints and length of each latus rectum. Then find the area of the rectangle whose four vertices are the latus-rectum endpoints.

Hints

- First locate the foci of the hyperbola. - A latus rectum passes through a focus and is perpendicular to the transverse axis. - Use the four symmetric endpoints to determine the rectangle's dimensions.

Solution

1. The hyperbola has \(a=4\), \(b^2=20\), and \(c=\sqrt{a^2+b^2}=6\), so the foci are \((\pm6, 0)\). 2. Each latus rectum is perpendicular to the transverse axis and passes through a focus, so its supporting line is \(x=6\) or \(x=-6\). 3. Substitute \(x=6\) into the hyperbola: \(\frac{36}{16}-\frac{y^2}{20}=1\). 4. This gives \(\frac{y^2}{20}=\frac54\), so \(y=\pm5\). 5. The four endpoints are \((6,\pm5)\) and \((-6,\pm5)\). 6. Each latus rectum has length \(10\). 7. The rectangle has width \(12\) and height \(10\), so its area is \(120\).

Answer

Latus-rectum endpoints: \((6,\pm5)\) and \((-6,\pm5)\) Length of each latus rectum: \(10\) Rectangle area: \(120\)
54399112
For the hyperbola \(\frac{(x-1)^2}{49}-\frac{(y+2)^2}{16}=1\), find the center, vertices, foci, asymptotes, and the acute angle between the asymptotes.

Hints

- Read the center and semi-axis parameters directly from standard form. - Use \(c^2=a^2+b^2\) for the foci. - The asymptote slopes determine equal and opposite direction angles from the horizontal.

Solution

1. The hyperbola is horizontal with center \((1, -2)\), \(a=7\), and \(b=4\). 2. The vertices are \((1\pm7,-2)\), or \((8,-2)\) and \((-6,-2)\). 3. The focal distance satisfies \(c^2=a^2+b^2=49+16=65\), so \(c=\sqrt{65}\). 4. The foci are \((1\pm\sqrt{65},-2)\). 5. The asymptotes are \(y+2=\pm\frac47(x-1)\). 6. Each asymptote makes an angle \(\arctan\left(\frac47\right)\) with the horizontal axis. Therefore the acute angle between them is \(2\arctan\left(\frac47\right)\approx59.5^\circ\).

Answer

Center: \((1,-2)\) Vertices: \((8,-2)\) and \((-6,-2)\) Foci: \((1+\sqrt{65},-2)\) and \((1-\sqrt{65},-2)\) Asymptotes: \(y+2=\pm\frac47(x-1)\) Acute angle: \(2\arctan\left(\frac47\right)\approx59.5^\circ\)
54371712
A hyperbola is centered at \((2, -1)\) and has a vertical transverse axis. One asymptote is \(y+1=\frac{3}{2}(x-2)\), and the point \((6, 8)\) lies on the hyperbola. Write the hyperbola in standard form and state its vertices.

Hints

- Start with the standard form that matches a vertical transverse axis. - Use the asymptote slope to relate the two denominator values. - Substitute the given point only after expressing both denominators with one common scale factor.

Solution

1. For a vertical hyperbola, the standard form is \(\frac{(y+1)^2}{a^2}-\frac{(x-2)^2}{b^2}=1\), and the asymptote slope is \(\frac{a}{b}\). 2. Since \(\frac{a}{b}=\frac{3}{2}\), let \(a^2=9k\) and \(b^2=4k\) for some positive \(k\). 3. Substituting \((6, 8)\) gives \(\frac{81}{9k}-\frac{16}{4k}=1\), so \(\frac{5}{k}=1\) and \(k=5\). 4. Thus \(a^2=45\) and \(b^2=20\), so the equation is \(\frac{(y+1)^2}{45}-\frac{(x-2)^2}{20}=1\). 5. Since \(a=3\sqrt{5}\), the vertices are \((2, -1+3\sqrt{5})\) and \((2, -1-3\sqrt{5})\).

Answer

The hyperbola is \(\frac{(y+1)^2}{45}-\frac{(x-2)^2}{20}=1\). Its vertices are \((2, -1+3\sqrt{5})\) and \((2, -1-3\sqrt{5})\).
54372412
A hyperbola has center \((-3, 2)\), vertices \((-3, 7)\) and \((-3, -3)\), and one asymptote passes through \((1, 8)\). Write the hyperbola in standard form and give equations for both asymptotes.

Hints

- Use the center and vertices to determine the transverse-axis direction and one semi-axis length. - Find the slope of the given asymptote from the two points on it. - Relate that slope to the dimensions of the hyperbola's asymptote rectangle.

Solution

1. The vertices are vertical from the center, so the hyperbola has a vertical transverse axis. Their distance from the center gives \(a=5\). 2. The slope from the center to \((1, 8)\) is \(\frac{8-2}{1-(-3)}=\frac{3}{2}\). 3. For a vertical hyperbola, an asymptote slope has magnitude \(\frac{a}{b}\). Thus \(\frac{5}{b}=\frac{3}{2}\), so \(b=\frac{10}{3}\) and \(b^2=\frac{100}{9}\). 4. The standard form is \(\frac{(y-2)^2}{25}-\frac{(x+3)^2}{100/9}=1\). 5. The asymptotes are \(y-2=\frac{3}{2}(x+3)\) and \(y-2=-\frac{3}{2}(x+3)\).

Answer

The hyperbola is \(\frac{(y-2)^2}{25}-\frac{(x+3)^2}{100/9}=1\). Its asymptotes are \(y-2=\frac{3}{2}(x+3)\) and \(y-2=-\frac{3}{2}(x+3)\).
54373712
A horizontal hyperbola is centered at the origin and has eccentricity \(\frac{5}{4}\). The rectangle with vertices \((\pm a, \pm b)\), whose diagonals lie along the hyperbola’s asymptotes, has area \(96\). Find the hyperbola’s standard equation and its asymptotes.

Hints

- Use eccentricity to relate the two semi-axis lengths. - Translate the rectangle’s area into a product involving those lengths. - The asymptote slopes come from the rectangle’s side-length ratio.

Solution

1. For a horizontal hyperbola, \(c^2=a^2+b^2\) and \(e=\frac{c}{a}=\frac{5}{4}\). 2. Thus \(\frac{b^2}{a^2}=e^2-1=\frac{25}{16}-1=\frac{9}{16}\), so \(b=\frac{3}{4}a\). 3. The rectangle has width \(2a\) and height \(2b\), so \(4ab=96\), or \(ab=24\). 4. Substituting \(b=\frac{3}{4}a\) gives \(\frac{3}{4}a^2=24\), so \(a^2=32\) and \(b^2=18\). 5. The equation is \(\frac{x^2}{32}-\frac{y^2}{18}=1\), and the asymptotes are \(y=\pm\frac{b}{a}x=\pm\frac{3}{4}x\).

Answer

\(\frac{x^2}{32}-\frac{y^2}{18}=1\) Asymptotes: \(y=\frac{3}{4}x\) and \(y=-\frac{3}{4}x\)
54375812
A horizontal hyperbola is centered at the origin, has vertices \((\pm3, 0)\), and has perpendicular asymptotes. Find its standard equation, asymptotes, foci, and eccentricity. Explain how perpendicularity determines the missing semi-axis.

Hints

- Write the two asymptote slopes in terms of the semi-axis lengths. - Use the condition for two nonvertical lines to be perpendicular. - After finding both semi-axes, determine the focal distance.

Solution

1. The vertices give \(a=3\). 2. The asymptotes of \(\frac{x^2}{a^2}-\frac{y^2}{b^2}=1\) have slopes \(\pm\frac{b}{a}\). 3. Their slope product is \(-\frac{b^2}{a^2}\). Perpendicular lines have slope product \(-1\), so \(b=a=3\). 4. The equation is \(\frac{x^2}{9}-\frac{y^2}{9}=1\), and the asymptotes are \(y=x\) and \(y=-x\). 5. Since \(c^2=a^2+b^2=18\), \(c=3\sqrt{2}\). The foci are \((\pm3\sqrt{2}, 0)\), and \(e=\frac{c}{a}=\sqrt{2}\).

Answer

Equation: \(\frac{x^2}{9}-\frac{y^2}{9}=1\) Asymptotes: \(y=x\), \(y=-x\) Foci: \((3\sqrt{2}, 0)\), \((-3\sqrt{2}, 0)\) Eccentricity: \(\sqrt{2}\)
54376512
For the hyperbola \(\frac{x^2}{36}-\frac{y^2}{25}=1\), determine how many finite intersection points the line \(y=mx\) has with the hyperbola for every real \(m\). Then find the intersection points when \(m=\frac{1}{2}\).

Hints

- Substitute the line through the center into the hyperbola. - The sign of the resulting coefficient of \(x^2\) controls whether real points exist. - Compare the boundary slopes with the hyperbola’s asymptotes.

Solution

1. Substitute \(y=mx\): \(x^2(\frac{1}{36}-\frac{m^2}{25})=1\). 2. If \(\frac{1}{36}-\frac{m^2}{25}>0\), there are two intersections. This occurs when \(|m|<\frac{5}{6}\). 3. If \(|m|=\frac{5}{6}\), the line is an asymptote and the equation becomes \(0=1\), so there is no finite intersection. 4. If \(|m|>\frac{5}{6}\), the coefficient is negative, so there is no real intersection. 5. For \(m=\frac{1}{2}\), \(x^2(\frac{1}{36}-\frac{1}{100})=1\), giving \(x^2=\frac{225}{4}\). 6. Thus the points are \((\frac{15}{2}, \frac{15}{4})\) and \((-\frac{15}{2}, -\frac{15}{4})\).

Answer

\(|m|<\frac{5}{6}\): two finite intersections \(|m|\ge\frac{5}{6}\): no finite intersections For \(m=\frac{1}{2}\): \((\frac{15}{2}, \frac{15}{4})\) and \((-\frac{15}{2}, -\frac{15}{4})\)
54377212
The point \(P=(7, \frac{13}{6})\) lies on the right branch of \(\frac{x^2}{36}-\frac{y^2}{13}=1\). Find the eccentricity, foci, and directrices. Then verify at \(P\) the focus–directrix ratio associated with the right branch.

Hints

- Determine the focal distance from the two denominator values. - Pair the right branch with the focus and directrix on the right. - Compute the two distances separately before taking their ratio.

Solution

1. Here \(a=6\), \(b^2=13\), and \(c^2=a^2+b^2=49\), so \(c=7\). 2. The foci are \((\pm7, 0)\), and the eccentricity is \(e=\frac{c}{a}=\frac{7}{6}\). 3. The directrices are \(x=\pm\frac{a}{e}=\pm\frac{36}{7}\). 4. For the right branch, pair the right focus \((7, 0)\) with the right directrix \(x=\frac{36}{7}\). 5. The distance from \(P\) to the right focus is \(\frac{13}{6}\). 6. The perpendicular distance from \(P\) to the right directrix is \(7-\frac{36}{7}=\frac{13}{7}\). 7. Their ratio is \(\frac{13/6}{13/7}=\frac{7}{6}=e\).

Answer

Eccentricity: \(\frac{7}{6}\) Foci: \((7, 0)\), \((-7, 0)\) Directrices: \(x=\frac{36}{7}\), \(x=-\frac{36}{7}\) At \(P\), \(\frac{PF}{\text{distance to directrix}}=\frac{13/6}{13/7}=\frac{7}{6}\).
54377712
A horizontal hyperbola is centered at the origin. Its asymptotes are \(y=\pm2x\), and its directrices are \(x=\pm3\). Find its standard equation, vertices, and foci.

Hints

- Use the asymptote slopes to relate the two semi-axis lengths. - Express eccentricity from that ratio. - Use the directrix distance to determine the scale of the hyperbola.

Solution

1. For \(\frac{x^2}{a^2}-\frac{y^2}{b^2}=1\), the asymptote slope gives \(\frac{b}{a}=2\), so \(b=2a\). 2. Then \(c^2=a^2+b^2=5a^2\), so \(c=a\sqrt{5}\) and \(e=\sqrt{5}\). 3. The directrix distance is \(\frac{a}{e}=\frac{a}{\sqrt{5}}\). Setting this equal to \(3\) gives \(a=3\sqrt{5}\). 4. Thus \(a^2=45\), \(b^2=180\), and \(c=15\). 5. The equation is \(\frac{x^2}{45}-\frac{y^2}{180}=1\). The vertices are \((\pm3\sqrt{5}, 0)\), and the foci are \((\pm15, 0)\).

Answer

\(\frac{x^2}{45}-\frac{y^2}{180}=1\) Vertices: \((3\sqrt{5}, 0)\), \((-3\sqrt{5}, 0)\) Foci: \((15, 0)\), \((-15, 0)\)
54378412
Find all intersection points of the hyperbola \(\frac{x^2}{9}-\frac{y^2}{16}=1\) and the circle \(x^2+y^2=25\).

Hints

- Both equations involve only squared coordinates. - Temporarily treat \(x^2\) and \(y^2\) as two unknowns in a linear system. - Recover all coordinate signs after finding the squared values.

Solution

1. Let \(X=x^2\) and \(Y=y^2\). The equations become \(\frac{X}{9}-\frac{Y}{16}=1\) and \(X+Y=25\). 2. Substitute \(Y=25-X\): \(\frac{X}{9}-\frac{25-X}{16}=1\). 3. Multiplying by \(144\) gives \(16X-9(25-X)=144\), so \(25X=369\) and \(X=\frac{369}{25}\). 4. Then \(Y=25-\frac{369}{25}=\frac{256}{25}\). 5. Therefore \(x=\pm\frac{3\sqrt{41}}{5}\) and \(y=\pm\frac{16}{5}\). Every independent sign combination satisfies both equations.

Answer

\((\pm\frac{3\sqrt{41}}{5}, \pm\frac{16}{5})\), with all four sign combinations
54379112
For the hyperbola \(\frac{(x-1)^2}{9}-\frac{(y+2)^2}{16}=1\), define the horizontal branch separation at height \(y\) as the distance between the left-branch and right-branch points having that y-coordinate. Find the minimum separation and the heights at which the separation is \(8\).

Hints

- Solve the hyperbola equation for both x-values at a fixed y-coordinate. - Subtract the left value from the right value. - Analyze the squared vertical displacement from the center to find minima and prescribed values.

Solution

1. Solve for the two x-values at a fixed height: \(x=1\pm3\sqrt{1+\frac{(y+2)^2}{16}}\). 2. Their separation is \(S(y)=6\sqrt{1+\frac{(y+2)^2}{16}}\). 3. This expression is minimized when \((y+2)^2=0\), so the minimum separation is \(6\) at \(y=-2\). 4. Set \(S(y)=8\): \(6\sqrt{1+\frac{(y+2)^2}{16}}=8\). 5. Squaring gives \(1+\frac{(y+2)^2}{16}=\frac{16}{9}\), so \((y+2)^2=\frac{112}{9}\). 6. Therefore \(y=-2\pm\frac{4\sqrt{7}}{3}\).

Answer

Minimum separation: \(6\), at \(y=-2\) Separation \(8\): \(y=-2+\frac{4\sqrt{7}}{3}\) and \(y=-2-\frac{4\sqrt{7}}{3}\)
54380512
Consider the confocal family of hyperbolas \(\frac{x^2}{a^2}-\frac{y^2}{25-a^2}=1\), where \(0<a<5\). Show that all members have the same foci. Then find the member whose asymptotes make \(45^\circ\) angles with the x-axis, and state its vertices.

Hints

- Compute the focal distance from the two denominator expressions. - Translate the asymptote angle into a slope condition. - Use that condition to determine the parameter value.

Solution

1. Here \(b^2=25-a^2\), so \(c^2=a^2+b^2=25\). Every member has foci \((\pm5, 0)\). 2. The asymptote slopes are \(\pm\frac{b}{a}=\pm\frac{\sqrt{25-a^2}}{a}\). 3. A \(45^\circ\) angle requires slope magnitude \(1\), so \(\sqrt{25-a^2}=a\). 4. Squaring gives \(25-a^2=a^2\), so \(a^2=\frac{25}{2}\). Then \(b^2=\frac{25}{2}\). 5. The required hyperbola is \(\frac{x^2}{25/2}-\frac{y^2}{25/2}=1\), with vertices \((\pm\frac{5}{\sqrt{2}}, 0)\).

Answer

Common foci: \((5, 0)\), \((-5, 0)\) Required equation: \(\frac{x^2}{25/2}-\frac{y^2}{25/2}=1\) Vertices: \((\frac{5}{\sqrt{2}}, 0)\), \((-\frac{5}{\sqrt{2}}, 0)\)
54381212
The hyperbola \(\frac{x^2}{9}-\frac{y^2}{4}=1\) is transformed by \(X=2x-1\) and \(Y=3y+2\). Find the transformed equation, center, vertices, foci, and asymptotes in the \(X, Y\)-plane.

Hints

- Invert the coordinate transformation before substituting. - Read the transformed hyperbola’s features from standard form. - Apply the equal-denominator case carefully when finding asymptotes and foci.

Solution

1. Invert the transformation: \(x=\frac{X+1}{2}\) and \(y=\frac{Y-2}{3}\). 2. Substitution gives \(\frac{(X+1)^2}{36}-\frac{(Y-2)^2}{36}=1\). 3. The center is \((-1, 2)\), and \(a^2=b^2=36\). 4. The vertices are \((-1\pm6, 2)\), or \((-7, 2)\) and \((5, 2)\). 5. Since \(c^2=a^2+b^2=72\), the foci are \((-1\pm6\sqrt{2}, 2)\). 6. The asymptotes are \(Y-2=\pm(X+1)\).

Answer

Equation: \(\frac{(X+1)^2}{36}-\frac{(Y-2)^2}{36}=1\) Center: \((-1, 2)\) Vertices: \((-7, 2)\), \((5, 2)\) Foci: \((-1\pm6\sqrt{2}, 2)\) Asymptotes: \(Y-2=\pm(X+1)\)
54385212
For a point \(P=(x, y)\) on the hyperbola \(\frac{x^2}{36}-\frac{y^2}{64}=1\), let \(d_1\) and \(d_2\) be the perpendicular distances from \(P\) to the two asymptotes. Prove that \(d_1d_2\) is constant, and find its value.

Hints

- Write each asymptote in the form \(Ax+By+C=0\). - Apply the point-to-line distance formula to the same point on both asymptotes. - Multiply the two distances and use a scaled version of the hyperbola equation.

Solution

1. The asymptotes are \(y=\pm\frac{4}{3}x\), or \(4x-3y=0\) and \(4x+3y=0\). 2. The distances are \(d_1=\frac{|4x-3y|}{5}\) and \(d_2=\frac{|4x+3y|}{5}\). 3. Their product is \(d_1d_2=\frac{|16x^2-9y^2|}{25}\). 4. Multiplying the hyperbola equation by \(576\) gives \(16x^2-9y^2=576\). 5. Therefore, \(d_1d_2=\frac{576}{25}\), independent of \(P\).

Answer

\(d_1d_2=\frac{576}{25}\) square units for every point on the hyperbola.
54385912
Consider the hyperbola \(\frac{x^2}{36}-\frac{y^2}{16}=1\). A nonvertical line through the center has equation \(y=mx\). Determine exactly which values of \(m\) make the line intersect the hyperbola. Explain how the boundary values are related to the asymptotes.

Hints

- Substitute the line equation into the hyperbola and isolate the coefficient multiplying \(x^2\). - A real value of \(x\) requires the resulting value of \(x^2\) to be positive. - Compare the boundary slopes of the inequality with \(\pm\frac{b}{a}\).

Solution

1. Substitute \(y=mx\) into the hyperbola: \(\frac{x^2}{36}-\frac{m^2x^2}{16}=1\). 2. Factor \(x^2\): \(x^2\left(\frac{1}{36}-\frac{m^2}{16}\right)=1\). 3. Real intersection points require the coefficient of \(x^2\) to be positive: \(\frac{1}{36}-\frac{m^2}{16}>0\). 4. This inequality gives \(m^2<\frac{4}{9}\), so \(-\frac{2}{3}<m<\frac{2}{3}\). 5. The hyperbola's asymptotes are \(y=\pm\frac{2}{3}x\). At the boundary slopes, the substituted equation becomes \(0=1\), so the asymptotes do not meet the hyperbola. 6. Lines through the center with slopes strictly between the asymptote slopes meet both branches; steeper lines do not meet the hyperbola.

Answer

The line intersects the hyperbola exactly when \(-\frac{2}{3}<m<\frac{2}{3}\). The boundary slopes \(m=\pm\frac{2}{3}\) are the slopes of the asymptotes, which do not intersect the hyperbola.
54386612
Rewrite \(4x^2-9y^2-16x-54y-101=0\) in standard form. Then state the center, vertices, and asymptotes of the hyperbola.

Hints

- Group the x-terms and y-terms and complete the square in each variable. - Divide so the right side is \(1\), then identify the positive squared term to determine the opening direction. - Translate the asymptote equations \(y=\pm\frac{b}{a}x\) to the hyperbola's center.

Solution

1. Group the variable terms: \(4(x^2-4x)-9(y^2+6y)=101\). 2. Complete the squares: \(4((x-2)^2-4)-9((y+3)^2-9)=101\). 3. Simplify to obtain \(4(x-2)^2-9(y+3)^2=36\). 4. Divide by \(36\): \(\frac{(x-2)^2}{9}-\frac{(y+3)^2}{4}=1\). 5. The center is \((2,-3)\), and \(a=3\), so the vertices are \((-1,-3)\) and \((5,-3)\). 6. For a horizontal hyperbola, the asymptotes are \(y-k=\pm\frac{b}{a}(x-h)\). 7. Therefore, the asymptotes are \(y+3=\pm\frac{2}{3}(x-2)\).

Answer

Standard form: \(\frac{(x-2)^2}{9}-\frac{(y+3)^2}{4}=1\) Center: \((2, -3)\) Vertices: \((-1, -3)\) and \((5, -3)\) Asymptotes: \(y+3=\pm\frac{2}{3}(x-2)\)
54388012
For the hyperbola \(\frac{x^2}{64}-\frac{y^2}{225}=1\), find all intersections of its two directrices with its two asymptotes. Then show that the four intersection points lie on one circle and identify the circle.

Hints

- Use \(c^2=a^2+b^2\) to find the eccentricity and then the directrices. - Intersect each vertical directrix with both asymptotes. - Compute the squared distance of an intersection point from the center and use symmetry for the other three.

Solution

1. The hyperbola has \(a=8\), \(b=15\), and \(c=\sqrt{64+225}=17\), so its eccentricity is \(e=\frac{17}{8}\). 2. Its directrices are \(x=\pm\frac{a}{e}=\pm\frac{64}{17}\). 3. Its asymptotes are \(y=\pm\frac{15}{8}x\). 4. Intersecting the directrices with the asymptotes gives \(\left(\pm\frac{64}{17},\pm\frac{120}{17}\right)\), with the signs chosen independently. 5. Each point has squared distance from the origin \(\frac{4096}{289}+\frac{14400}{289}=64\). 6. Therefore, all four points lie on the circle \(x^2+y^2=64\).

Answer

Intersection points: \(\left(\pm\frac{64}{17}, \pm\frac{120}{17}\right)\), with signs chosen independently Common circle: \(x^2+y^2=64\)
54388712
Consider the upper half of the right branch of \(\frac{(x-1)^2}{16}-\frac{(y+2)^2}{25}=1\) and its upper asymptote. a) Find the branch point and the asymptote point with \(x=9\), and determine their vertical separation. b) Repeat for \(x=17\). c) Explain how the two results illustrate asymptotic behavior.

Hints

- Write both the upper branch and the upper asymptote as formulas for \(y\). - At each specified x-coordinate, evaluate both formulas before subtracting their y-values. - Compare the two positive gaps to describe what “approaches an asymptote” means numerically.

Solution

1. The upper asymptote is \(y+2=\frac{5}{4}(x-1)\). 2. On the upper branch, \(y+2=5\sqrt{\frac{(x-1)^2}{16}-1}\). 3. At \(x=9\), the branch point is \((9,-2+5\sqrt{3})\), while the asymptote point is \((9,8)\). 4. Their vertical separation is \(8-(-2+5\sqrt{3})=10-5\sqrt{3}\). 5. At \(x=17\), the branch point is \((17,-2+5\sqrt{15})\), while the asymptote point is \((17,18)\). 6. Their vertical separation is \(18-(-2+5\sqrt{15})=20-5\sqrt{15}\). 7. Since \(20-5\sqrt{15}<10-5\sqrt{3}\), the branch is closer to the asymptote farther from the center, while never meeting it.

Answer

a) Branch point: \((9, -2+5\sqrt{3})\); asymptote point: \((9, 8)\); separation: \(10-5\sqrt{3}\) b) Branch point: \((17, -2+5\sqrt{15})\); asymptote point: \((17, 18)\); separation: \(20-5\sqrt{15}\) c) The separation decreases as \(x\) increases, illustrating that the branch approaches the asymptote.
54389412
A hyperbola is centered at the origin, opens left and right, has asymptotes \(y=\pm\frac{3}{2}x\), and passes through \(\left(5,\frac{9}{2}\right)\). Write its equation in standard form and state its vertices.

Hints

- Use the asymptote slopes to determine the ratio \(\frac{b}{a}\). - Represent both semi-axis lengths with one positive scale factor, then substitute the known point. - The vertices of a horizontal hyperbola lie \(a\) units from the center on the x-axis.

Solution

1. A horizontal hyperbola centered at the origin has equation \(\frac{x^2}{a^2}-\frac{y^2}{b^2}=1\), with asymptote slopes \(\pm\frac{b}{a}\). 2. Since \(\frac{b}{a}=\frac{3}{2}\), write \(a=2k\) and \(b=3k\), where \(k>0\). 3. Substitute the given point: \(\frac{25}{4k^2}-\frac{81/4}{9k^2}=1\). 4. Simplifying gives \(\frac{4}{k^2}=1\), so \(k=2\). 5. Therefore, \(a=4\) and \(b=6\), and the equation is \(\frac{x^2}{16}-\frac{y^2}{36}=1\). 6. The vertices are \((-4,0)\) and \((4,0)\).

Answer

Equation: \(\frac{x^2}{16}-\frac{y^2}{36}=1\) Vertices: \((-4, 0)\) and \((4, 0)\)
54394312
The hyperbola \(\frac{x^2}{36}-\frac{y^2}{64}=1\) has asymptotes \(L_1:4x-3y=0\) and \(L_2:4x+3y=0\). Find every point \(P\) on the hyperbola whose perpendicular distance to \(L_1\) is twice its perpendicular distance to \(L_2\).

Hints

- Apply the point-to-line distance formula to both asymptotes. - Split the absolute-value equation into its two possible linear cases. - Substitute each candidate line into the hyperbola and reject any case with no real points.

Solution

1. The distances are \(d_1=\frac{|4x-3y|}{5}\) and \(d_2=\frac{|4x+3y|}{5}\). 2. The condition \(d_1=2d_2\) becomes \(|4x-3y|=2|4x+3y|\). 3. One case is \(4x-3y=2(4x+3y)\), which simplifies to \(4x+9y=0\), or \(x=-\frac{9}{4}y\). 4. Substitution into the hyperbola gives \(\frac{y^2}{8}=1\), so \(y=\pm2\sqrt{2}\) and \(x=\mp\frac{9\sqrt{2}}{2}\). 5. The other case is \(4x-3y=-2(4x+3y)\), which gives \(y=-4x\). Substitution makes the left side of the hyperbola equation negative, so it gives no real points.

Answer

The points are \(\left(-\frac{9\sqrt{2}}{2}, 2\sqrt{2}\right)\) and \(\left(\frac{9\sqrt{2}}{2}, -2\sqrt{2}\right)\).
54397712
A vertical hyperbola is centered at \((-2, 3)\). Its foci are \((-2, 13)\) and \((-2, -7)\), and its asymptotes have slopes \(\pm\frac34\). Find the hyperbola's standard equation, vertices, and asymptote equations.

Hints

- Find the focal distance from the center to either focus. - For a vertical hyperbola, use \(\frac{a}{b}\) for the asymptote-slope magnitude. - Combine the ratio with \(c^2=a^2+b^2\) to determine both semi-axis parameters.

Solution

1. The focal distance is \(c=10\). 2. For a vertical hyperbola, the asymptote slopes are \(\pm\frac{a}{b}\). Thus \(\frac{a}{b}=\frac34\). 3. Write \(a=3k\) and \(b=4k\). Then \(c^2=a^2+b^2=9k^2+16k^2=25k^2\). 4. Since \(c=10\), \(5k=10\), so \(k=2\). Therefore \(a=6\) and \(b=8\). 5. The standard equation is \(\frac{(y-3)^2}{36}-\frac{(x+2)^2}{64}=1\). 6. The vertices are \((-2, 3\pm6)\), or \((-2, 9)\) and \((-2, -3)\). 7. The asymptotes are \(y-3=\pm\frac34(x+2)\).

Answer

Equation: \(\frac{(y-3)^2}{36}-\frac{(x+2)^2}{64}=1\) Vertices: \((-2, 9)\) and \((-2, -3)\) Asymptotes: \(y-3=\pm\frac34(x+2)\)
54398612
A centered horizontal hyperbola has asymptotes \(y=\pm\frac{5}{12}x\). Each latus rectum has total length \(\frac{25}{6}\). Determine the hyperbola's standard equation, vertices, foci, and directrices.

Hints

- Relate the asymptote slopes to the two semi-axis parameters. - Use the latus-rectum information as a second independent condition. - After finding the semi-axes, use the focal relationship for a hyperbola.

Solution

1. Write the hyperbola as \(\frac{x^2}{a^2}-\frac{y^2}{b^2}=1\), where \(a>0\) and \(b>0\). 2. The asymptote slope gives \(\frac{b}{a}=\frac{5}{12}\), so \(b=\frac{5a}{12}\). 3. A latus rectum has length \(\frac{2b^2}{a}\). Therefore, \(\frac{2}{a}\left(\frac{5a}{12}\right)^2=\frac{25}{6}\), which simplifies to \(a=12\). 4. Then \(b=5\), so the standard equation is \(\frac{x^2}{144}-\frac{y^2}{25}=1\). 5. Since \(c^2=a^2+b^2=169\), \(c=13\). The vertices are \((\pm12, 0)\), and the foci are \((\pm13, 0)\). 6. The eccentricity is \(e=\frac{13}{12}\), so the directrices are \(x=\pm\frac{a}{e}=\pm\frac{144}{13}\).

Answer

Standard equation: \(\frac{x^2}{144}-\frac{y^2}{25}=1\) Vertices: \((\pm12, 0)\) Foci: \((\pm13, 0)\) Directrices: \(x=\pm\frac{144}{13}\)
54374412
The graph shows the upper half of the right branch of \(\frac{x^2}{36}-\frac{y^2}{16}=1\) and its upper-right asymptote. a) Find the vertical gap between the curve and the asymptote at \(x=15\). b) Find the least x-coordinate beyond which this vertical gap is less than \(0.2\).
Figure for problem 543744

Hints

- Solve the hyperbola equation for the positive y-value and compare it with the positive-slope asymptote. - Rationalize the difference \(x-\sqrt{x^2-a^2}\) before solving the inequality. - Find the boundary where the gap equals \(0.2\), then use how the gap changes along the branch.

Solution

1. The upper branch is \(y=\frac{2}{3}\sqrt{x^2-36}\), and the upper-right asymptote is \(y=\frac{2}{3}x\). 2. At \(x=15\), the gap is \(10-\frac{2}{3}\sqrt{189}=10-2\sqrt{21}\approx0.835\). 3. For \(x\ge6\), the gap is \(D=\frac{2}{3}(x-\sqrt{x^2-36})\). 4. Rationalizing gives \(D=\frac{24}{x+\sqrt{x^2-36}}\). 5. Set the boundary value equal to \(0.2\): \(x+\sqrt{x^2-36}=120\). 6. Squaring \(\sqrt{x^2-36}=120-x\) gives \(x=\frac{1203}{20}\). The gap decreases as \(x\) increases, so it is below \(0.2\) when \(x>\frac{1203}{20}\).

Answer

a) \(10-2\sqrt{21}\approx0.835\) b) The gap is less than \(0.2\) for \(x>\frac{1203}{20}\approx60.15\).
54395012
A horizontal hyperbola is centered at the origin. Its two foci are \(34\) units apart. The guide rectangle whose vertices are \((\pm a, \pm b)\) has perimeter \(92\). Find every possible standard equation of the hyperbola. For each possibility, state the vertices and asymptotes.

Hints

- Translate the focal separation into a relationship involving the two semi-axis parameters. - Translate the guide rectangle's perimeter into a second relationship. - The given information may determine the two parameter values without determining which one is the transverse semi-axis.

Solution

1. The focal separation is \(2c=34\), so \(c=17\) and \(a^2+b^2=c^2=289\). 2. The guide rectangle has side lengths \(2a\) and \(2b\). Its perimeter is \(4(a+b)=92\), so \(a+b=23\). 3. Square the sum: \(529=a^2+2ab+b^2=289+2ab\), so \(ab=120\). 4. The positive numbers \(a\) and \(b\) are therefore the roots of \(z^2-23z+120=0\), giving \(\{a,b\}=\{8,15\}\). 5. If \(a=8\) and \(b=15\), the equation is \(\frac{x^2}{64}-\frac{y^2}{225}=1\), with vertices \((\pm8, 0)\) and asymptotes \(y=\pm\frac{15}{8}x\). 6. If \(a=15\) and \(b=8\), the equation is \(\frac{x^2}{225}-\frac{y^2}{64}=1\), with vertices \((\pm15, 0)\) and asymptotes \(y=\pm\frac{8}{15}x\).

Answer

Possibility 1: \(\frac{x^2}{64}-\frac{y^2}{225}=1\) Vertices: \((\pm8, 0)\) Asymptotes: \(y=\pm\frac{15}{8}x\) Possibility 2: \(\frac{x^2}{225}-\frac{y^2}{64}=1\) Vertices: \((\pm15, 0)\) Asymptotes: \(y=\pm\frac{8}{15}x\)

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