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Solving Right Triangles worksheet with diagrams and problems.

Worksheet with 10 right triangle diagrams for solving using the Pythagorean Theorem.

Worksheet with 10 right triangle diagrams for solving using the Pythagorean Theorem.

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Show Answer Key & Explanations Step-by-step solution for: Solving Right Triangles Worksheet for 7th - 10th Grade | Lesson Planet
Let’s solve each right triangle problem one by one. We’ll use trigonometry (sine, cosine, tangent) and the Pythagorean theorem where needed. All answers will be rounded to the nearest tenth.

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Problem 1:
Given: angle = 30°, adjacent side = 48, find opposite side (x)

Use tangent:
tan(θ) = opposite / adjacent
tan(30°) = x / 48
x = 48 × tan(30°)
tan(30°) ≈ 0.5774
x ≈ 48 × 0.5774 ≈ 27.7

Answer for #1: x ≈ 27.7

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Problem 2:
Given: angle = 62°, hypotenuse = 19, find adjacent side (x)

Use cosine:
cos(θ) = adjacent / hypotenuse
cos(62°) = x / 19
x = 19 × cos(62°)
cos(62°) ≈ 0.4695
x ≈ 19 × 0.4695 ≈ 8.9

Answer for #2: x ≈ 8.9

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Problem 3:
Given: angle = 52°, opposite side = 20, find hypotenuse (x)

Use sine:
sin(θ) = opposite / hypotenuse
sin(52°) = 20 / x
x = 20 / sin(52°)
sin(52°) ≈ 0.7880
x ≈ 20 / 0.7880 ≈ 25.4

Answer for #3: x ≈ 25.4

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Problem 4:
Given: angle = 55°, adjacent side = 16, find hypotenuse (x)

Use cosine:
cos(55°) = adjacent / hypotenuse = 16 / x
x = 16 / cos(55°)
cos(55°) ≈ 0.5736
x ≈ 16 / 0.5736 ≈ 27.9

Answer for #4: x ≈ 27.9

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Problem 5:
Given: angle = 25°, opposite side = 21, find adjacent side (x)

Use tangent:
tan(25°) = opposite / adjacent = 21 / x
x = 21 / tan(25°)
tan(25°) ≈ 0.4663
x ≈ 21 / 0.4663 ≈ 45.0

Answer for #5: x ≈ 45.0

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Problem 6:
Given: angle = 58°, hypotenuse = 13, find opposite side (x)

Use sine:
sin(58°) = opposite / hypotenuse = x / 13
x = 13 × sin(58°)
sin(58°) ≈ 0.8480
x ≈ 13 × 0.8480 ≈ 11.0

Answer for #6: x ≈ 11.0

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Problem 7:
Given: two legs are 5 and 12, find hypotenuse (x) — this is a right triangle with no angles given, so use Pythagorean theorem.

a² + b² = c²
5² + 12² = x²
25 + 144 = x²
169 = x²
x = √169 = 13.0

Answer for #7: x = 13.0

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Problem 8:
Given: angle = 35°, adjacent side = 12, find opposite side (x)

Use tangent:
tan(35°) = x / 12
x = 12 × tan(35°)
tan(35°) ≈ 0.7002
x ≈ 12 × 0.7002 ≈ 8.4

Answer for #8: x ≈ 8.4

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Problem 9:
Given: two legs are 10 and 10, find hypotenuse (x) — again, use Pythagorean theorem.

10² + 10² = x²
100 + 100 = x²
200 = x²
x = √200 ≈ 14.142 → round to 14.1

Answer for #9: x ≈ 14.1

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Problem 10:
Given: angle = 30°, hypotenuse = 20, find adjacent side (x)

Use cosine:
cos(30°) = x / 20
x = 20 × cos(30°)
cos(30°) ≈ 0.8660
x ≈ 20 × 0.8660 ≈ 17.3

Answer for #10: x ≈ 17.3

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Final Answer:
1. 27.7
2. 8.9
3. 25.4
4. 27.9
5. 45.0
6. 11.0
7. 13.0
8. 8.4
9. 14.1
10. 17.3
Parent Tip: Review the logic above to help your child master the concept of right triangle worksheet.
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