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Pythagorean theorem problem solving

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5144638
In a coordinate plane, points \(A(0, 0)\), \(B(w, 0)\), and \(C(w, h)\) form a right triangle with leg lengths \(w\) and \(h\). Use the Pythagorean theorem to analyze the hypotenuse length \(d\). a) \(w = 1\) and \(h = 1\) b) \(w = 3\) and \(h = 4\) Based on these cases, evaluate the claim: “The diagonal of a square or rectangle with integer side lengths is never rational.”

Hints

- Use the Pythagorean theorem. - When is the square root of a natural number rational? - Look for familiar integer side-length combinations in right triangles.

Solution

1. For a), \(d = \sqrt{1^2 + 1^2} = \sqrt{2}\), which is irrational. 2. For b), \(d = \sqrt{3^2 + 4^2} = \sqrt{25} = 5\), which is rational. 3. Case b) is a counterexample to the claim because a rectangle with integer side lengths \(3\) and \(4\) has rational diagonal length \(5\). Therefore, the claim is false.

Answer

a) \(d = \sqrt{2}\), which is irrational. b) \(d = 5\), which is rational. The claim is false; a \(3\)-by-\(4\) rectangle has diagonal length \(5\).
5150048
Find the diagonal \(d\) of a rectangle with side lengths \(1.2\,\text{m}\) and \(3.5\,\text{m}\).

Hints

- A diagonal divides a rectangle into two right triangles. - Use the rectangle’s side lengths as the legs.

Solution

1. The side lengths and diagonal form a right triangle. 2. By the Pythagorean theorem, \(d^2=1.2^2+3.5^2=1.44+12.25=13.69\). 3. Therefore, \(d=\sqrt{13.69}=3.7\,\text{m}\).

Answer

\(d=3.7\,\text{m}\)
5150258
A square sheet of paper has side length \(20\,\text{cm}\). It is folded exactly along a diagonal. Find the length of the crease, rounded to the nearest tenth of a centimeter.

Hints

- A diagonal divides a square into two isosceles right triangles. - Use the two side lengths as the legs.

Solution

1. The diagonal is the hypotenuse of an isosceles right triangle with legs \(20\,\text{cm}\). 2. By the Pythagorean theorem, \(d^2=20^2+20^2=800\). 3. Thus \(d=\sqrt{800}=20\sqrt{2}\,\text{cm}\approx 28.3\,\text{cm}\).

Answer

The crease is approximately \(28.3\,\text{cm}\) long.
5150358
Solve each right-triangle problem. The legs are \(a\) and \(b\), and the hypotenuse is \(c\). a) \(a=\sqrt{13}\) and \(b=\sqrt{23}\). Find the exact value of \(c\). b) \(c=15\) and \(a=9\). Find \(b\).

Hints

- Squaring a square root returns the number under the radical. - Rearrange the Pythagorean theorem for the unknown side. - Identify the hypotenuse before substituting.

Solution

1. Part a: \(c^2=(\sqrt{13})^2+(\sqrt{23})^2=13+23=36\), so \(c=6\). 2. Part b: \(b^2=15^2-9^2=225-81=144\), so \(b=12\).

Answer

a) \(c=6\) b) \(b=12\)
5152508
A square garden has a diagonal of exactly \(20\,\text{ft}\). 1. Briefly explain why the Pythagorean theorem can be used to find the side length. 2. Find the side length \(a\). Give an exact value and a decimal approximation rounded to the nearest hundredth.

Hints

- Draw the diagonal and identify the right triangle. - The two legs have the same length. - Simplify the radical before rounding.

Solution

1. A diagonal divides a square into two congruent right triangles. The square’s sides are the legs, and the diagonal is the hypotenuse. 2. Therefore, \(a^2+a^2=20^2\), so \(2a^2=400\) and \(a^2=200\). 3. Thus \(a=\sqrt{200}=10\sqrt{2}\,\text{ft}\approx 14.14\,\text{ft}\).

Answer

1. The diagonal divides the square into two right triangles. 2. \(a=10\sqrt{2}\,\text{ft}\approx 14.14\,\text{ft}\)
5154488
A square traffic sign has diagonal length \(60\,\text{in.}\). Find its area.

Hints

- A diagonal divides the square into two right triangles. - You can solve directly for \(a^2\), which is also the area.

Solution

1. If the side length is \(a\), then \(60^2=a^2+a^2=2a^2\). 2. Therefore, \(a^2=\frac{3600}{2}=1800\). 3. Since the square’s area is \(a^2\), the area is \(1800\,\text{in.}^2\).

Answer

The area is \(1800\,\text{in.}^2\).
5155898
A tablet has a rectangular display that is \(9\,\text{in.}\) by \(12\,\text{in.}\). A protective sleeve is designed for tablets with display diagonals no longer than \(14\,\text{in.}\). Use a calculation to determine whether the tablet will fit the sleeve.

Hints

- What geometric shape models the display? - How are the side lengths of a rectangle related to its diagonal? - Compare the diagonal you calculate with the sleeve's limit.

Solution

1. Model the display as a rectangle with side lengths \(9\,\text{in.}\) and \(12\,\text{in.}\). 2. Use the Pythagorean theorem: \(d^2=9^2+12^2\). 3. Simplify: \(d^2=81+144=225\), so \(d=15\,\text{in.}\). 4. Because \(15\,\text{in.}>14\,\text{in.}\), the tablet does not meet the sleeve's size limit.

Answer

No. The display diagonal is \(15\,\text{in.}\), which is longer than the sleeve's \(14\,\text{in.}\) limit.
5245298
Find the missing leg \(b\) in each right triangle. a) The hypotenuse is \(37\,\text{cm}\), and the other leg is \(12\,\text{cm}\). b) The hypotenuse is \(2.5\,\text{m}\), and the other leg is \(1.5\,\text{m}\).

Hints

- Recall the relationship among the three side lengths of a right triangle. - Identify the hypotenuse before substituting values. - Rearrange the formula when a leg, rather than the hypotenuse, is unknown.

Solution

1. Rearrange the Pythagorean theorem to solve for the missing leg: \(b=\sqrt{c^2-a^2}\). 2. For a), \(b=\sqrt{37^2-12^2}=\sqrt{1369-144}=\sqrt{1225}=35\,\text{cm}\). 3. For b), \(b=\sqrt{2.5^2-1.5^2}=\sqrt{6.25-2.25}=\sqrt{4}=2\,\text{m}\).

Answer

a) \(b=35\,\text{cm}\) b) \(b=2\,\text{m}\)
5364348
Find the missing side length \(x\) in the right triangle shown.
Figure for problem 536434

Hints

- Decide whether the unknown side is a leg or the hypotenuse. - Use the relationship among the squared side lengths of a right triangle. - The hypotenuse is opposite the right angle.

Solution

1. The unknown side is the hypotenuse, and the legs are \(5\,\text{cm}\) and \(12\,\text{cm}\). 2. Apply the Pythagorean theorem: \(x^2=5^2+12^2=25+144=169\). 3. Since a length is positive, \(x=\sqrt{169}=13\,\text{cm}\).

Answer

\(x=13\,\text{cm}\)
5364358
One leg of the right triangle is unknown. Find \(x\).
Figure for problem 536435

Hints

- Identify the hypotenuse before writing the equation. - Rearrange the Pythagorean equation when a leg is unknown. - Subtract the square of the known leg from the square of the hypotenuse.

Solution

1. The hypotenuse is \(25\,\text{cm}\), the known leg is \(7\,\text{cm}\), and the other leg is \(x\). 2. Apply the Pythagorean theorem: \(x^2+7^2=25^2\). 3. Solve for \(x^2\): \(x^2=625-49=576\). 4. Since a length is positive, \(x=\sqrt{576}=24\,\text{cm}\).

Answer

\(x=24\,\text{cm}\)
5364368
Find the missing leg length \(x\). Pay attention to the different units shown in the diagram.
Figure for problem 536436

Hints

- Express all side lengths in the same unit before calculating. - Choose the unit that avoids unnecessary decimals. - Rearrange the equation so that the square of the unknown side is isolated.

Solution

1. Convert the hypotenuse to centimeters: \(1\,\text{dm}=10\,\text{cm}\). 2. Apply the Pythagorean theorem: \(x^2+6^2=10^2\). 3. Solve: \(x^2=100-36=64\), so \(x=\sqrt{64}=8\,\text{cm}\).

Answer

\(x=8\,\text{cm}\)
5364388
Find the hypotenuse length \(x\) in the triangle shown.
Figure for problem 536438

Hints

- Make sure both given lengths use the same unit. - Identify the hypotenuse. - Add the squares of the legs to find the square of the hypotenuse.

Solution

1. Express both legs in decimeters: \(0.7\,\text{m}=7\,\text{dm}\). The legs are \(7\,\text{dm}\) and \(24\,\text{dm}\). 2. Apply the Pythagorean theorem: \(x^2=7^2+24^2=49+576=625\). 3. Since a length is positive, \(x=\sqrt{625}=25\,\text{dm}\).

Answer

\(x=25\,\text{dm}\)
5364558
A square has side length \(a\). Derive a formula for its diagonal length \(d\) in terms of \(a\).
Figure for problem 536455

Hints

- What triangle is formed when a square is divided along a diagonal? - Apply the Pythagorean theorem to that right triangle. - Simplify the radical as far as possible.

Solution

1. Two adjacent sides and the diagonal form a right triangle with legs \(a\) and \(a\). 2. By the Pythagorean theorem, \(d^2=a^2+a^2=2a^2\). 3. Since a length is positive, \(d=\sqrt{2a^2}=a\sqrt{2}\).

Answer

\(d=a\sqrt{2}\)
5364778
Find the length of side \(x\). All measurements are in centimeters.
Figure for problem 536477

Hints

- Identify the hypotenuse and the two legs. - Use the Pythagorean theorem. - Check whether the unknown is a leg or the hypotenuse.

Solution

1. The side \(x\) is the hypotenuse, and the legs have lengths \(4.8\,\text{cm}\) and \(3.6\,\text{cm}\). 2. Apply the Pythagorean theorem: \(x^2=4.8^2+3.6^2=23.04+12.96=36\). 3. Therefore, \(x=\sqrt{36}=6\,\text{cm}\).

Answer

\(x=6\,\text{cm}\)
5369178
Rectangle \(ABCD\) has side lengths \(12\,\text{cm}\) and \(5\,\text{cm}\). Find the length of diagonal \(AC\).
Figure for problem 536917

Hints

- A diagonal divides a rectangle into two right triangles. - Use the two side lengths as the legs.

Solution

1. Two adjacent sides and the diagonal form a right triangle. 2. Apply the Pythagorean theorem: \(AC^2=12^2+5^2=169\). 3. Therefore, \(AC=13\,\text{cm}\).

Answer

\(AC=13\,\text{cm}\)
5369188
A rectangle has a diagonal of length \(17\,\text{cm}\). One side is \(8\,\text{cm}\) long. Find the length of the other side.
Figure for problem 536918

Hints

- The side lengths and diagonal form a right triangle. - Rearrange the Pythagorean theorem to find a leg.

Solution

1. The diagonal is the hypotenuse of a right triangle formed by the rectangle’s side lengths. 2. Let the unknown side be \(b\). Then \(b^2=17^2-8^2=289-64=225\). 3. Therefore, \(b=15\,\text{cm}\).

Answer

The other side is \(15\,\text{cm}\) long.
5150068
A rectangular park is \(120\,\text{yd}\) wide and \(160\,\text{yd}\) long. A walker can go directly from one corner to the opposite corner or follow two sides of the park. How much shorter is the direct route?

Hints

- The direct route is the hypotenuse of a right triangle. - Find both route lengths separately, then subtract.

Solution

1. The route along two sides is \(120+160=280\,\text{yd}\). 2. The direct route is the diagonal: \(d^2=120^2+160^2=40{,}000\), so \(d=200\,\text{yd}\). 3. The difference is \(280-200=80\,\text{yd}\).

Answer

The direct route is \(80\,\text{yd}\) shorter.
5150078
A triangle has side lengths \(a = 15\,\text{cm}\), \(b = 20\,\text{cm}\), and \(c = 24\,\text{cm}\). a) Use calculations to explain why the triangle is not a right triangle. b) Keeping \(a\) and \(b\) unchanged, find the length of \(c\) that would make a right triangle with \(c\) as the hypotenuse.

Hints

- Recall how the converse of the Pythagorean theorem relates the three side lengths. - Compare the sum of the squares of the two shorter sides with the square of the longest side. - For the right-triangle case, use \(c\) as the hypotenuse in the Pythagorean theorem.

Solution

1. a) The longest side is \(c = 24\,\text{cm}\). Compare \(a^2 + b^2\) with \(c^2\): \(15^2 + 20^2 = 225 + 400 = 625\), while \(24^2 = 576\). Since \(625 \ne 576\), the triangle is not a right triangle. 2. b) For \(c\) to be the hypotenuse, \(c^2 = 15^2 + 20^2 = 625\). Therefore, \(c = \sqrt{625} = 25\,\text{cm}\).

Answer

a) The triangle is not a right triangle because \(15^2 + 20^2 = 625 \ne 576 = 24^2\). b) \(c = 25\,\text{cm}\).
5150088
A carpenter is checking whether two beams form a right angle. The beams are \(12\,\text{ft}\) and \(16\,\text{ft}\) long, and the measured diagonal between their endpoints is \(20.5\,\text{ft}\). a) Show that the frame is not exactly square. b) Find the diagonal length required for a right angle. c) If the carpenter keeps the \(20.5\,\text{ft}\) diagonal and the \(16\,\text{ft}\) beam, how long should the other beam be? Round to the nearest hundredth of a foot.

Hints

- Treat the beams as legs and the diagonal as the hypotenuse. - Compare the sum of the squares of the beam lengths with the square of the measured diagonal. - Rearrange the Pythagorean theorem for the unknown leg in part c.

Solution

1. Check the converse of the Pythagorean theorem: \(12^2+16^2=400\), while \(20.5^2=420.25\). Because the values are not equal, the angle is not a right angle. 2. For a right angle with beams \(12\,\text{ft}\) and \(16\,\text{ft}\), \(d=\sqrt{12^2+16^2}=20\,\text{ft}\). 3. Keeping the \(20.5\,\text{ft}\) diagonal and the \(16\,\text{ft}\) beam, let the other beam be \(a\). Then \(a^2=20.5^2-16^2=164.25\), so \(a\approx 12.82\,\text{ft}\).

Answer

a) The frame is not square because \(12^2+16^2=400\ne 420.25=20.5^2\). b) \(20\,\text{ft}\) c) Approximately \(12.82\,\text{ft}\)
5150108
A rectangle has diagonal \(d=17\,\text{cm}\) and one side \(a=15\,\text{cm}\). Find its area \(A\) and perimeter \(P\).

Hints

- Use the diagonal and known side to find the missing side. - Then apply the rectangle area and perimeter formulas.

Solution

1. Find the missing side: \(b^2=17^2-15^2=64\), so \(b=8\,\text{cm}\). 2. The area is \(A=15\cdot 8=120\,\text{cm}^2\). 3. The perimeter is \(P=2(15+8)=46\,\text{cm}\).

Answer

The area is \(120\,\text{cm}^2\), and the perimeter is \(46\,\text{cm}\).
5150128
A rectangular wooden gate is \(3\,\text{ft}\) wide and has area \(12\,\text{ft}^2\). A diagonal brace will be installed from one corner to the opposite corner. How long should the brace be?

Hints

- Use the area and width to find the gate’s height. - Then use the Pythagorean theorem for the diagonal.

Solution

1. Find the height from the area: \(h=\frac{12}{3}=4\,\text{ft}\). 2. The brace is the rectangle’s diagonal, so \(d=\sqrt{3^2+4^2}=5\,\text{ft}\).

Answer

The brace should be \(5\,\text{ft}\) long.
5150168
A triangle has side lengths \(0.7\,\text{m}\), \(2.4\,\text{m}\), and \(250\,\text{cm}\). First determine whether it is a right triangle. Then find its area.

Hints

- Convert all side lengths to the same unit. - Compare the sum of the squares of the two shorter sides with the square of the longest side. - If the triangle is right, use its legs as the base and height.

Solution

1. Convert \(250\,\text{cm}\) to \(2.5\,\text{m}\). 2. Check the converse of the Pythagorean theorem: \(0.7^2+2.4^2=0.49+5.76=6.25\), and \(2.5^2=6.25\). Therefore, the triangle is right. 3. The legs are \(0.7\,\text{m}\) and \(2.4\,\text{m}\), so \(A=\frac{1}{2}\cdot 0.7\cdot 2.4=0.84\,\text{m}^2\).

Answer

The triangle is right, and its area is \(0.84\,\text{m}^2\).
5150218
A flagpole should stand perpendicular to a level schoolyard. To check it, a teacher attaches a \(5.20\,\text{m}\) rope to a point on the pole that is \(4.00\,\text{m}\) above the base. The rope is pulled tight and anchored \(3.30\,\text{m}\) from the base of the pole. Determine whether the pole is exactly perpendicular to the ground. If it is not, find the exact rope length needed for a perpendicular pole with the same vertical distance of \(4.00\,\text{m}\) and horizontal distance of \(3.30\,\text{m}\). Also give the length to the nearest hundredth of a meter.

Hints

- What geometric figure is formed by the pole, the ground, and the taut rope? - Which segment would be the hypotenuse if the pole were perpendicular to the ground? - How can you find the third side length when the included angle is \(90^\circ\)?

Solution

1. If the pole is perpendicular to the ground, the pole segment and ground distance are the legs, and the rope is the hypotenuse. 2. Calculate \(4.00^2 + 3.30^2 = 16.00 + 10.89 = 26.89\). 3. Calculate \(5.20^2 = 27.04\). Since \(26.89 \ne 27.04\), the pole is not exactly perpendicular to the ground. 4. The required rope length is \(\sqrt{4.00^2 + 3.30^2} = \sqrt{26.89}\,\text{m}\). 5. Since \(\sqrt{26.89} \approx 5.1856\), the rope should be about \(5.19\,\text{m}\) long.

Answer

The pole is not exactly perpendicular. The required rope length is exactly \(\sqrt{26.89}\,\text{m}\), or approximately \(5.19\,\text{m}\).
5150228
Four ropes have marked segments that can be used as the side lengths of a triangular garden bed. The numbers give the segment lengths in units: Rope A: \(9, 12, 15\) Rope B: \(7, 10, 18\) Rope C: \(10, 10, 14\) Rope D: \(5, 12, 13\) a) One rope cannot form a triangle at all. Identify it and justify your answer mathematically. b) Which of the remaining ropes can form an exact right triangle? Show the calculations that support your answer.

Hints

- What condition must three lengths satisfy to form a closed triangle? - What relationship among the squared side lengths shows that a triangle is right? - Is equality in the triangle inequality enough to form a triangle? - Which side must be treated as the possible hypotenuse?

Solution

1. a) For Rope B, the two shorter lengths add to \(7 + 10 = 17\), which is less than \(18\). Therefore, Rope B cannot form a triangle. 2. b) Rope A satisfies \(9^2 + 12^2 = 81 + 144 = 225 = 15^2\), so it forms a right triangle. 3. Rope C gives \(10^2 + 10^2 = 200\), while \(14^2 = 196\), so it does not form a right triangle. 4. Rope D satisfies \(5^2 + 12^2 = 25 + 144 = 169 = 13^2\), so it forms a right triangle.

Answer

a) Rope B cannot form a triangle because \(7 + 10 < 18\). b) Ropes A and D form right triangles because \(9^2 + 12^2 = 15^2\) and \(5^2 + 12^2 = 13^2\).
5150238
A landscaper has a \(60\,\text{m}\) rope and wants to use its full length to mark the perimeter of a right triangle. All three side lengths, \(a\), \(b\), and \(c\), must be whole numbers of meters. Find two different sets of side lengths and show that each set forms a right triangle.

Hints

- Recall a simple whole-number triple that satisfies the Pythagorean theorem. - Scaling all three sides of a right triangle by the same factor preserves the right angle. - The three side lengths must add to exactly \(60\).

Solution

1. A scaled \((3, 4, 5)\) triangle can have perimeter \(60\,\text{m}\). Since \(3+4+5=12\) and \(60 \div 12=5\), scale each side by \(5\) to get \(15\), \(20\), and \(25\). The perimeter is \(60\), and \(15^2+20^2=225+400=625=25^2\). 2. A scaled \((5, 12, 13)\) triangle also works. Since \(5+12+13=30\) and \(60 \div 30=2\), scale each side by \(2\) to get \(10\), \(24\), and \(26\). The perimeter is \(60\), and \(10^2+24^2=100+576=676=26^2\).

Answer

1. \(15\,\text{m}, 20\,\text{m}, 25\,\text{m}\), because \(15+20+25=60\) and \(15^2+20^2=25^2\). 2. \(10\,\text{m}, 24\,\text{m}, 26\,\text{m}\), because \(10+24+26=60\) and \(10^2+24^2=26^2\).
5150348
Find the missing side length in each right triangle. The legs are \(a\) and \(b\), and the hypotenuse is \(c\). Pay attention to the units. a) \(a=15\,\text{cm}\), \(b=20\,\text{cm}\). Find \(c\). b) \(a=0.8\,\text{dm}\), \(c=1.7\,\text{dm}\). Find \(b\). c) \(b=120\,\text{mm}\), \(c=13\,\text{cm}\). Find \(a\).

Hints

- Identify whether the missing side is a leg or the hypotenuse. - Convert measurements to the same unit before calculating. - Use the Pythagorean theorem in each part.

Solution

1. For a), \(c=\sqrt{15^2+20^2}=25\,\text{cm}\). 2. For b), \(b=\sqrt{1.7^2-0.8^2}=\sqrt{2.25}=1.5\,\text{dm}\). 3. For c), convert \(120\,\text{mm}=12\,\text{cm}\). Then \(a=\sqrt{13^2-12^2}=5\,\text{cm}\).

Answer

a) \(c=25\,\text{cm}\) b) \(b=1.5\,\text{dm}\) c) \(a=5\,\text{cm}\)
5150378
A rectangular field is \(5\,\text{yd}\) wide, and its diagonal is \(13\,\text{yd}\). Find the other side length \(b\) and the area \(A\).

Hints

- A diagonal divides the rectangle into two right triangles. - Find the missing side before finding the area.

Solution

1. The diagonal is the hypotenuse, so \(b^2=13^2-5^2=144\). Thus \(b=12\,\text{yd}\). 2. The area is \(A=5\cdot 12=60\,\text{yd}^2\).

Answer

\(b=12\,\text{yd}\) and \(A=60\,\text{yd}^2\)
5150548
A smartphone screen has a diagonal of \(6.8\,\text{in.}\) and a visible height of \(6.0\,\text{in.}\). a) Find the screen width. b) Write the width-to-height aspect ratio as a ratio of whole numbers in simplest form.

Hints

- The screen dimensions and diagonal form a right triangle. - After finding the width, clear the decimals in the ratio and reduce it.

Solution

1. Let the width be \(w\). Then \(w^2+6.0^2=6.8^2\), so \(w^2=46.24-36=10.24\). 2. Therefore, \(w=3.2\,\text{in.}\). 3. The ratio \(3.2:6.0\) becomes \(32:60\), which simplifies to \(8:15\).

Answer

a) \(3.2\,\text{in.}\) b) \(8:15\)
5154458
Two right triangles share a leg \(k\). The first triangle has hypotenuse \(17\,\text{cm}\) and another leg of \(8\,\text{cm}\). The second triangle has legs \(k\) and \(20\,\text{cm}\). Find the hypotenuse \(x\) of the second triangle.

Hints

- Find the shared leg from the first triangle. - Then use that leg in the second triangle. - Identify the hypotenuse in each triangle.

Solution

1. In the first triangle, \(k^2=17^2-8^2=225\), so \(k=15\,\text{cm}\). 2. In the second triangle, \(x^2=15^2+20^2=625\), so \(x=25\,\text{cm}\).

Answer

\(x=25\,\text{cm}\)
5154468
A quadrilateral lot is made of two right triangles that share a side \(s\). In the first triangle, \(s\) is a leg, the hypotenuse is \(25\,\text{yd}\), and the other leg is \(7\,\text{yd}\). In the second triangle, the legs are \(s\) and \(10\,\text{yd}\). Find the total area of the lot.

Hints

- Find the shared side from the first right triangle. - Use the legs of each right triangle as its base and height. - Add the two areas.

Solution

1. In the first triangle, \(s^2=25^2-7^2=576\), so \(s=24\,\text{yd}\). 2. The first area is \(A_1=\frac{1}{2}\cdot 7\cdot 24=84\,\text{yd}^2\). 3. The second area is \(A_2=\frac{1}{2}\cdot 24\cdot 10=120\,\text{yd}^2\). 4. The total area is \(84+120=204\,\text{yd}^2\).

Answer

The total area is \(204\,\text{yd}^2\).
5188208
Point \(R\) is \(5\,\text{cm}\) from line \(m\). Point \(S\) is on the same side of \(m\) as \(R\) and is \(2\,\text{cm}\) from \(m\). a) What is the least possible length of \(\overline{RS}\)? b) Can \(\overline{RS}\) be \(4\,\text{cm}\) long? Justify your answer.

Hints

- The shortest segment between two parallel lines is perpendicular to them. - The difference between the two given distances is one leg of a right triangle. - For part b, use the Pythagorean theorem.

Solution

1. The least distance occurs when \(R\) and \(S\) lie on the same line perpendicular to \(m\). Their distances from \(m\) differ by \(5-2=3\,\text{cm}\), so the least possible length is \(3\,\text{cm}\). 2. Yes. If the component of \(\overline{RS}\) perpendicular to \(m\) is \(3\,\text{cm}\), choose a parallel component \(x\) so that \(x^2+3^2=4^2\). 3. This gives \(x^2=7\), so an offset of \(\sqrt{7}\,\text{cm}\) produces a segment of length \(4\,\text{cm}\).

Answer

a) \(3\,\text{cm}\) b) Yes. A sideways offset of \(\sqrt{7}\,\text{cm}\) gives \(RS=4\,\text{cm}\).
5188228
Point \(A\) is \(4\,\text{cm}\) from line \(g\), and point \(B\) is \(2\,\text{cm}\) from \(g\). The points lie on opposite sides of \(g\). Decide whether each statement is true or false. Explain your reasoning. a) Segment \(\overline{AB}\) is at least \(6\,\text{cm}\) long. b) Segment \(\overline{AB}\) can be only \(2\,\text{cm}\) long. c) If \(AB=6\,\text{cm}\), then \(\overline{AB}\) is perpendicular to \(g\).

Hints

- The segment must cross line \(g\). - Add the two perpendicular distances to find the shortest possible route. - Think about when that shortest route is achieved.

Solution

1. Because \(A\) and \(B\) are on opposite sides of \(g\), the perpendicular component of \(\overline{AB}\) across the line is \(4+2=6\,\text{cm}\). 2. Any additional component parallel to \(g\) makes \(\overline{AB}\) longer than \(6\,\text{cm}\). Therefore, \(AB\ge 6\,\text{cm}\), so statement a is true and statement b is false. 3. Equality occurs only when there is no component parallel to \(g\). In that case, \(\overline{AB}\) follows one perpendicular line through \(g\), so statement c is true.

Answer

a) True. The least possible length is \(4+2=6\,\text{cm}\). b) False. \(AB\) cannot be less than \(6\,\text{cm}\). c) True. The minimum occurs only when \(\overline{AB}\perp g\).
5233118
A rectangular prism has edge lengths \(a=12\,\text{cm}\) and \(b=9\,\text{cm}\). Its space diagonal is \(d=17\,\text{cm}\). a) Find the missing edge length \(c\). b) Find the volume \(V\) of the prism.

Hints

- How are the three edge lengths of a rectangular prism related to its space diagonal? - Rearrange the equation so that the missing edge length is the only unknown. - Which formula gives the volume of a rectangular prism?

Solution

1. Apply the Pythagorean theorem in three dimensions: \(d^2=a^2+b^2+c^2\). 2. Solve for \(c\): \(c=\sqrt{d^2-a^2-b^2}=\sqrt{17^2-12^2-9^2}=\sqrt{64}=8\,\text{cm}\). 3. Use \(V=abc\): \(V=12\cdot9\cdot8=864\,\text{cm}^3\).

Answer

a) \(c=8\,\text{cm}\) b) \(V=864\,\text{cm}^3\)
5241558
Points \(A(2, 2)\), \(B(8, 2)\), and \(C(5, 6)\) form triangle \(ABC\). a) Find the length of \(\overline{AB}\). b) Use the Pythagorean theorem to find the lengths of \(\overline{AC}\) and \(\overline{BC}\). c) Classify the triangle by its side lengths.

Hints

- A horizontal segment’s length is the difference of its x-coordinates. - Use the horizontal and vertical changes as the legs of a right triangle. - A triangle with two equal side lengths has a special classification.

Solution

1. Segment \(\overline{AB}\) is horizontal, so \(AB = 8 - 2 = 6\) units. 2. From \(A\) to \(C\), the horizontal change is \(3\) and the vertical change is \(4\). Therefore, \(AC = \sqrt{3^2 + 4^2} = \sqrt{25} = 5\) units. 3. From \(B\) to \(C\), the horizontal change has magnitude \(3\) and the vertical change is \(4\). Therefore, \(BC = \sqrt{3^2 + 4^2} = 5\) units. 4. Since \(AC = BC\), the triangle is isosceles.

Answer

a) \(AB = 6\) units b) \(AC = 5\) units and \(BC = 5\) units c) The triangle is isosceles.
5245308
A right triangle has a hypotenuse of \(29\,\text{cm}\) and one leg of \(21\,\text{cm}\). 1. Find the length of the other leg \(b\). 2. The hypotenuse is increased by \(6\,\text{cm}\) while the \(21\,\text{cm}\) leg stays the same. By how many centimeters does \(b\) increase?

Hints

- First find the unknown side in the original triangle. - Determine the new hypotenuse after the change. - Repeat the calculation for the new triangle, then compare the two leg lengths.

Solution

1. For the original triangle, \(b=\sqrt{29^2-21^2}=\sqrt{841-441}=\sqrt{400}=20\,\text{cm}\). 2. The new hypotenuse is \(29+6=35\,\text{cm}\). 3. The new leg length is \(b_{\text{new}}=\sqrt{35^2-21^2}=\sqrt{1225-441}=\sqrt{784}=28\,\text{cm}\). 4. The increase is \(28-20=8\,\text{cm}\).

Answer

1. \(b=20\,\text{cm}\) 2. The leg increases by \(8\,\text{cm}\).
5251858
Two hikers leave a trail intersection at the same time. Hiker A walks due north at \(4\,\text{mph}\), and Hiker B walks due west at \(3\,\text{mph}\). How far apart are they after \(2\) hours?

Hints

- Draw a sketch of the two paths. - What geometric figure is formed by the paths and the direct segment between the hikers? - First determine how far each hiker travels. - Use the relationship among the side lengths of a right triangle.

Solution

1. Hiker A travels \(4\cdot 2=8\,\text{mi}\). 2. Hiker B travels \(3\cdot 2=6\,\text{mi}\). 3. The two paths are perpendicular, so the hikers' separation is the hypotenuse of a right triangle. 4. Apply the Pythagorean theorem: \(d=\sqrt{8^2+6^2}=\sqrt{64+36}=\sqrt{100}=10\,\text{mi}\).

Answer

The hikers are \(10\,\text{mi}\) apart after \(2\) hours.
5251868
A sailboat starts \(15\) miles due north of a lighthouse and travels due east at \(12\,\text{mph}\). At the same time, a motorboat leaves the lighthouse and travels due north at \(4\,\text{mph}\). Find the distance between the boats after \(2\) hours.

Hints

- Place the lighthouse at the origin of a coordinate plane. - Determine each boat's position after \(2\) hours. - Find the horizontal and vertical separations between the boats. - Use those separations as the legs of a right triangle.

Solution

1. After \(2\) hours, the sailboat is \(12\cdot 2=24\,\text{mi}\) east of its starting point and remains \(15\,\text{mi}\) north of the lighthouse. 2. The motorboat is \(4\cdot 2=8\,\text{mi}\) north of the lighthouse. 3. The horizontal separation is \(24\,\text{mi}\), and the vertical separation is \(15-8=7\,\text{mi}\). 4. Use the Pythagorean theorem: \(d=\sqrt{24^2+7^2}=\sqrt{576+49}=\sqrt{625}=25\,\text{mi}\).

Answer

The boats are \(25\,\text{mi}\) apart after \(2\) hours.
5315908
A right triangular prism has a base with perpendicular legs \(3\,\text{cm}\) and \(4\,\text{cm}\). The prism is \(8\,\text{cm}\) long. a) Find the volume. b) Find the lateral surface area. c) Find the total surface area.
Figure for problem 531590

Hints

- Find the area of the right triangular base. - Use the Pythagorean theorem to find the third side. - Multiply the base perimeter by the prism length for lateral surface area. - Include both triangular bases for total surface area.

Solution

1. The triangular base area is \(B=\frac{1}{2}\cdot3\cdot4=6\,\text{cm}^2\). 2. The volume is \(V=6\cdot8=48\,\text{cm}^3\). 3. By the Pythagorean theorem, the hypotenuse is \(\sqrt{3^2+4^2}=5\,\text{cm}\). 4. The base perimeter is \(3+4+5=12\,\text{cm}\), so the lateral surface area is \(L=12\cdot8=96\,\text{cm}^2\). 5. The total surface area is \(S=2\cdot6+96=108\,\text{cm}^2\).

Answer

a) \(48\,\text{cm}^3\) b) \(96\,\text{cm}^2\) c) \(108\,\text{cm}^2\)
5315918
A tent has the shape of a right triangular prism. Its isosceles triangular end has base \(2.4\,\text{m}\) and height \(1.6\,\text{m}\). The tent is \(3.0\,\text{m}\) long. a) Find the interior volume. b) Find the total area of fabric used, including the floor.
Figure for problem 531591

Hints

- Find the area of the triangular end. - Use the Pythagorean theorem to find each slanted side. - For surface area, include both triangular ends and all three rectangular faces. - The floor is one of the rectangular faces.

Solution

1. The triangular end area is \(B=\frac{1}{2}\cdot2.4\cdot1.6=1.92\,\text{m}^2\). 2. The volume is \(V=1.92\cdot3.0=5.76\,\text{m}^3\). 3. The triangle's altitude divides its base into two segments of \(1.2\,\text{m}\). By the Pythagorean theorem, each equal side is \(\sqrt{1.2^2+1.6^2}=2.0\,\text{m}\). 4. The triangular perimeter is \(2.4+2.0+2.0=6.4\,\text{m}\). 5. The total fabric area is \(S=2B+Pl=2\cdot1.92+6.4\cdot3.0=23.04\,\text{m}^2\).

Answer

a) \(5.76\,\text{m}^3\) b) \(23.04\,\text{m}^2\)
5315958
The right prism shown has an isosceles triangular base. The triangle has base \(6\,\text{cm}\) and corresponding height \(4\,\text{cm}\). The prism is \(12\,\text{cm}\) long. a) Find the base area and the prism's volume. b) Find the length of each equal side of the triangle, then find the lateral surface area and total surface area of the prism.
Figure for problem 531595

Hints

- Find the area of the triangular base first. - The altitude of an isosceles triangle bisects its base. - Use the Pythagorean theorem to find an equal side. - Use the base perimeter to find lateral surface area.

Solution

1. The triangular base area is \(B=\frac{1}{2}\cdot6\cdot4=12\,\text{cm}^2\). 2. The volume is \(V=12\cdot12=144\,\text{cm}^3\). 3. The altitude bisects the base into two \(3\,\text{cm}\) segments. By the Pythagorean theorem, each equal side is \(s=\sqrt{3^2+4^2}=5\,\text{cm}\). 4. The base perimeter is \(6+5+5=16\,\text{cm}\), so the lateral surface area is \(L=16\cdot12=192\,\text{cm}^2\). 5. The total surface area is \(S=2\cdot12+192=216\,\text{cm}^2\).

Answer

a) \(B=12\,\text{cm}^2\) and \(V=144\,\text{cm}^3\) b) \(s=5\,\text{cm}\), \(L=192\,\text{cm}^2\), and \(S=216\,\text{cm}^2\)
5364398
Find the missing side length \(x\) and give the result in meters.
Figure for problem 536439

Hints

- Convert the measurements to the same unit. - The unknown side is a leg, not the hypotenuse. - Remember to take the square root after finding \(x^2\).

Solution

1. Convert the known leg to meters: \(10\,\text{dm}=1\,\text{m}\). The hypotenuse is \(2.6\,\text{m}\). 2. Apply the Pythagorean theorem: \(x^2+1^2=2.6^2\). 3. Solve: \(x^2=6.76-1=5.76\), so \(x=\sqrt{5.76}=2.4\,\text{m}\).

Answer

\(x=2.4\,\text{m}\)
5364408
Find the side length \(x\) in millimeters.
Figure for problem 536440

Hints

- Decide whether \(x\) is a leg or the hypotenuse. - Convert all measurements to millimeters before calculating. - A calculator may help with the squares and square root.

Solution

1. Convert the known leg to millimeters: \(1.5\,\text{cm}=15\,\text{mm}\). The hypotenuse is \(39\,\text{mm}\). 2. Apply the Pythagorean theorem: \(x^2+15^2=39^2\). 3. Solve: \(x^2=1521-225=1296\), so \(x=\sqrt{1296}=36\,\text{mm}\).

Answer

\(x=36\,\text{mm}\)
5364468
A \(10\,\text{m}\) ladder leans against a wall. Its base is \(6\,\text{m}\) from the wall. Mia calculates the height \(h\) where the ladder touches the wall: \(h^2=10^2+6^2=136\), so \(h=\sqrt{136}\approx11.7\,\text{m}\). Explain why this result is unreasonable and find the correct height.
Figure for problem 536446

Hints

- Identify the right angle and determine which side is the hypotenuse. - Compare Mia’s result with the ladder length. - When a leg is unknown, decide whether to add or subtract squared lengths.

Solution

1. The ladder is the hypotenuse, so a leg cannot be longer than the \(10\,\text{m}\) ladder. A height of \(11.7\,\text{m}\) is therefore impossible. 2. Mia added the square of the known leg instead of subtracting it from the square of the hypotenuse. 3. The correct equation is \(h^2=10^2-6^2=100-36=64\). 4. Therefore, \(h=\sqrt{64}=8\,\text{m}\).

Answer

Mia’s result is unreasonable because a leg cannot be longer than the hypotenuse. The correct height is \(h=8\,\text{m}\).
5364788
Find the length of \(x\). All measurements are in centimeters.
Figure for problem 536478

Hints

- First find the common vertical leg of the two right triangles. - Use the total base length for the larger triangle.

Solution

1. Let \(h\) be the vertical leg shared by the two right triangles. In the smaller triangle, \(h^2=12.5^2-3.5^2=156.25-12.25=144\), so \(h=12\,\text{cm}\). 2. The base of the larger triangle is \(3.5+1.5=5\,\text{cm}\). 3. Apply the Pythagorean theorem to the larger triangle: \(x^2=12^2+5^2=169\). Therefore, \(x=13\,\text{cm}\).

Answer

\(x=13\,\text{cm}\)
5366098
Find the length of the marked segment \(x\). All measurements are in centimeters.
Figure for problem 536609

Hints

- The figure contains two right triangles that share a side. - Find the shared height from the left triangle first. - Then use that value in the right triangle to find \(x\).

Solution

1. Let \(h\) be the vertical segment shared by the two right triangles. In the left triangle, \(h^2+6^2=10^2\), so \(h^2=64\). 2. In the right triangle, \(x^2=h^2+15^2=64+225=289\). 3. Therefore, \(x=\sqrt{289}=17\,\text{cm}\).

Answer

\(x=17\,\text{cm}\)
5366128
The diagram shows a right triangle with an interior segment. Find \(x\). All measurements are in centimeters.
Figure for problem 536612

Hints

- Start with the smaller right triangle to find the shared vertical leg. - Use the total base length for the larger right triangle. - Apply the Pythagorean theorem again to find \(x\).

Solution

1. Let \(h\) be the vertical leg shared by the two right triangles. In the smaller triangle, \(h^2+7^2=25^2\), so \(h^2=625-49=576\). 2. The full base of the larger triangle is \(7+3=10\,\text{cm}\). 3. Apply the Pythagorean theorem to the larger triangle: \(x^2=576+10^2=676\). Therefore, \(x=26\,\text{cm}\).

Answer

\(x=26\,\text{cm}\)
5369928
A right triangle has hypotenuse \(13\,\text{cm}\) and one leg \(5\,\text{cm}\). Find its area.
Figure for problem 536992

Hints

- Use the Pythagorean theorem to find the missing leg. - Then use the two legs as the base and height.

Solution

1. Find the other leg \(b\): \(b^2=13^2-5^2=144\), so \(b=12\,\text{cm}\). 2. The area is \(A=\frac{1}{2}\cdot 5\cdot 12=30\,\text{cm}^2\).

Answer

The area is \(30\,\text{cm}^2\).
5138908
A sprinkler stands at the center of a square lawn with side length \(40\,\text{ft}\). It waters a circular region with radius \(20\,\text{ft}\). a) Find the square lawn's area and the percent of the lawn that is watered. b) Four congruent dry regions remain in the corners. Find the area of one dry corner. c) What sprinkler radius would just reach all four corners?

Hints

- Think of a circle centered in a square. - Find the part-to-whole percent using the two areas. - Divide the total dry area equally among the four corners. - Use the Pythagorean theorem from the center to a corner.

Solution

1. The square area is \(40\,\text{ft}\cdot40\,\text{ft}=1600\,\text{ft}^2\). 2. The watered area is \(\pi(20\,\text{ft})^2=400\pi\,\text{ft}^2\). The percent watered is \(\frac{400\pi}{1600}\cdot100\%=25\pi\%\approx78.54\%\). 3. The total dry area is \(1600-400\pi\,\text{ft}^2\), so one dry corner has area \(\frac{1600-400\pi}{4}\,\text{ft}^2\approx85.84\,\text{ft}^2\). 4. The required radius is the distance from the square's center to a corner. A right triangle has legs \(20\,\text{ft}\) and \(20\,\text{ft}\), so \(r=\sqrt{20^2+20^2}\,\text{ft}=20\sqrt{2}\,\text{ft}\approx28.28\,\text{ft}\).

Answer

a) \(1600\,\text{ft}^2\); approximately \(78.54\%\) watered b) Approximately \(85.84\,\text{ft}^2\) c) Approximately \(28.28\,\text{ft}\)
5150248
A loop of rope is divided into \(12\) equal segments and can be arranged as a right triangle with side lengths \(3\), \(4\), and \(5\) segments. Now consider ropes with different total numbers of equal segments. a) A worker claims that a rope with \(10\) segments can form a right triangle with whole-number side lengths. Explain mathematically why this is impossible. b) Another rope has \(30\) segments. Show that it can form a right triangle with whole-number side lengths whose side-length ratio is not \(3:4:5\).

Hints

- Use the triangle inequality to limit the possible length of the longest side when the perimeter is \(10\). - List the whole-number triples that add to \(10\) after applying that limit. - For part b), look for a Pythagorean triple that is not a scaled \((3, 4, 5)\) triple. - Compare corresponding side ratios to decide whether two triangles are scaled copies.

Solution

1. a) Let the whole-number side lengths satisfy \(a \le b \le c\) and \(a+b+c=10\). The triangle inequality gives \(a+b>c\), so \(10-c>c\) and therefore \(c<5\). Also, because all three sides are at most \(c\), \(3c \ge 10\), so the whole number \(c\) must be at least \(4\). Thus, \(c=4\). 2. Then \(a+b=6\). With \(a \le b \le 4\), the only possibilities are \((a, b)=(2, 4)\) and \((a, b)=(3, 3)\). Neither works: \(2^2+4^2=20 \ne 16\), and \(3^2+3^2=18 \ne 16\). Therefore, no whole-number right triangle has perimeter \(10\). 3. b) The side lengths \(5\), \(12\), and \(13\) have perimeter \(30\). They form a right triangle because \(5^2+12^2=25+144=169=13^2\). 4. The ratio \(5:12:13\) is not a scaled version of \(3:4:5\), because the corresponding scale factors are not equal.

Answer

a) No whole-number right triangle has perimeter \(10\). The only possible longest side is \(4\), and the remaining possibilities \((2, 4, 4)\) and \((3, 3, 4)\) do not satisfy the Pythagorean theorem. b) The side lengths \(5\), \(12\), and \(13\) have perimeter \(30\) and satisfy \(5^2+12^2=13^2\). Their ratio is not \(3:4:5\).
5150528
A television must fit in a cabinet opening that is \(36\,\text{in.}\) wide and \(24\,\text{in.}\) high. The television has a \(1\,\text{in.}\) bezel on all four sides of the screen. What is the largest whole-number screen size, measured diagonally, for a \(16:9\) television that will fit?

Hints

- Subtract the bezel twice from each cabinet dimension. - Use the \(16:9\) ratio to determine which dimension limits the screen. - Find the diagonal with the Pythagorean theorem, then choose the greatest whole number that does not exceed it.

Solution

1. The maximum screen dimensions are \(36-2\cdot 1=34\,\text{in.}\) wide and \(24-2\cdot 1=22\,\text{in.}\) high. 2. At the maximum width, a \(16:9\) screen has height \(34\cdot\frac{9}{16}=19.125\,\text{in.}\), which is less than \(22\,\text{in.}\). Thus width is the limiting dimension. 3. The maximum screen diagonal is \(d=\sqrt{34^2+19.125^2}\approx 39.01\,\text{in.}\). 4. Therefore, the largest whole-number screen size that fits is \(39\,\text{in.}\).

Answer

The largest whole-number screen size is \(39\,\text{in.}\).
5233128
A rectangular prism has edge lengths \(16\,\text{cm}\), \(8\,\text{cm}\), and \(4\,\text{cm}\). A cube has exactly the same volume. a) Find the cube edge length \(s\). b) Find the space diagonal of each solid. How many centimeters longer is the rectangular prism's space diagonal than the cube's space diagonal? Round the difference to the nearest hundredth.

Hints

- First find the volume of the rectangular prism. - How can you recover a cube's edge length from its volume? - Use the three-dimensional Pythagorean theorem for each space diagonal. - Round only after finding the difference.

Solution

1. The rectangular prism has volume \(V=16\cdot8\cdot4=512\,\text{cm}^3\). 2. For the cube, \(s^3=512\), so \(s=\sqrt[3]{512}=8\,\text{cm}\). 3. The rectangular prism's space diagonal is \(d_r=\sqrt{16^2+8^2+4^2}=\sqrt{336}\approx18.33\,\text{cm}\). 4. The cube's space diagonal is \(d_c=\sqrt{8^2+8^2+8^2}=\sqrt{192}=8\sqrt{3}\approx13.86\,\text{cm}\). 5. The difference is \(\sqrt{336}-\sqrt{192}\approx4.47\,\text{cm}\).

Answer

a) \(s=8\,\text{cm}\) b) Rectangular prism: \(d_r\approx18.33\,\text{cm}\); cube: \(d_c\approx13.86\,\text{cm}\). The rectangular prism's diagonal is approximately \(4.47\,\text{cm}\) longer.
5316008
The right prism shown has a symmetric trapezoidal base. The trapezoid has parallel sides \(10\,\text{cm}\) and \(4\,\text{cm}\), and height \(4\,\text{cm}\). The prism is \(15\,\text{cm}\) long. a) Find the base area and volume. b) Find the length of each slanted side of the trapezoid, then find the prism's total surface area.
Figure for problem 531600

Hints

- Use the trapezoid area formula. - Use symmetry to split the difference between the parallel sides equally. - Apply the Pythagorean theorem to one side triangle. - Use the base perimeter to find lateral surface area.

Solution

1. The trapezoidal base area is \(B=\frac{10+4}{2}\cdot4=28\,\text{cm}^2\). 2. The volume is \(V=28\cdot15=420\,\text{cm}^3\). 3. The difference between the parallel sides is \(10-4=6\,\text{cm}\). Symmetry gives a horizontal offset of \(3\,\text{cm}\) on each side. 4. By the Pythagorean theorem, each slanted side is \(s=\sqrt{3^2+4^2}=5\,\text{cm}\). 5. The base perimeter is \(10+5+4+5=24\,\text{cm}\), so the lateral surface area is \(L=24\cdot15=360\,\text{cm}^2\). 6. The total surface area is \(S=2\cdot28+360=416\,\text{cm}^2\).

Answer

a) \(B=28\,\text{cm}^2\) and \(V=420\,\text{cm}^3\) b) Each slanted side is \(5\,\text{cm}\), and \(S=416\,\text{cm}^2\).
5316228
The right prism shown has a house-shaped pentagonal base. The base is \(8\,\text{cm}\) wide, the vertical walls are \(5\,\text{cm}\) tall, and the total height to the roof peak is \(8\,\text{cm}\). The prism is \(15\,\text{cm}\) long. a) Find the base area. b) Find the volume. c) Find the length of each slanted roof edge. d) Find the lateral surface area and total surface area.
Figure for problem 531622

Hints

- Split the house-shaped base into a rectangle and a triangle. - Use symmetry and the Pythagorean theorem to find a roof edge. - Multiply the base perimeter by the prism length for lateral surface area. - Include both pentagonal bases.

Solution

1. The rectangular part has area \(8\cdot5=40\,\text{cm}^2\). The roof triangle has height \(8-5=3\,\text{cm}\) and area \(\frac{1}{2}\cdot8\cdot3=12\,\text{cm}^2\). Thus, \(B=52\,\text{cm}^2\). 2. The volume is \(V=52\cdot15=780\,\text{cm}^3\). 3. Half the roof triangle has legs \(4\,\text{cm}\) and \(3\,\text{cm}\). By the Pythagorean theorem, each slanted roof edge is \(\sqrt{4^2+3^2}=5\,\text{cm}\). 4. The base perimeter is \(8+5+5+5+5=28\,\text{cm}\), so the lateral surface area is \(L=28\cdot15=420\,\text{cm}^2\). 5. The total surface area is \(S=2\cdot52+420=524\,\text{cm}^2\).

Answer

a) \(52\,\text{cm}^2\) b) \(780\,\text{cm}^3\) c) Each slanted roof edge is \(5\,\text{cm}\). d) \(L=420\,\text{cm}^2\) and \(S=524\,\text{cm}^2\)
5359118
A rooftop cargo box is a prism with the pentagonal end shown. The bottom edge is \(120\,\text{cm}\), the left vertical side is \(50\,\text{cm}\), and the right vertical side is \(20\,\text{cm}\). From the upper left corner, the top runs horizontally for \(80\,\text{cm}\) and then slopes down to the upper right corner. The box is \(100\,\text{cm}\) deep. a) Find the box's volume in liters. b) Find its total surface area in square meters.
Figure for problem 535911

Hints

- Decompose the pentagonal end into rectangles and a triangle. - Use the Pythagorean theorem to find the slanted edge. - Use the end area for volume and its perimeter for lateral surface area. - Convert cubic centimeters to liters and square centimeters to square meters.

Solution

1. Decompose the end into an \(80\,\text{cm}\times50\,\text{cm}\) rectangle, a \(40\,\text{cm}\times20\,\text{cm}\) rectangle, and a right triangle with legs \(40\,\text{cm}\) and \(30\,\text{cm}\). 2. The end area is \(B=4000+800+\frac{1}{2}\cdot40\cdot30=5400\,\text{cm}^2\). 3. The volume is \(V=5400\cdot100=540{,}000\,\text{cm}^3=540\,\text{L}\). 4. The slanted edge has length \(\sqrt{40^2+30^2}=50\,\text{cm}\). 5. The end perimeter is \(120+20+50+80+50=320\,\text{cm}\), so the lateral surface area is \(L=320\cdot100=32{,}000\,\text{cm}^2\). 6. The total surface area is \(S=2\cdot5400+32{,}000=42{,}800\,\text{cm}^2=4.28\,\text{m}^2\).

Answer

a) \(540\,\text{L}\) b) \(4.28\,\text{m}^2\)

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