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9th Grade Circumference and Area of Circles Worksheet — Level 3 — Answers

Answer sheet with worked solutions for the 9th Grade area & perimeter worksheet.

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Success TutoringWorksheetsAnswer sheet9th Grade · Mathematics · Area & Perimeter

9th Grade Circumference and Area of Circles Worksheet — Level 3 — Answers

Show your work. Use the π button on your calculator and round to 1 decimal place unless told otherwise.

1.Find the area of a semicircle with a radius of 16 cm, correct to 1 decimal place.

Answer: 402.1 cm2

  1. A = ½ × π × r2 = ½ × π × 256
  2. ≈ 402.1 cm2
2.A circle has a diameter of 30 cm. Find its area, correct to 1 decimal place.

Answer: 706.9 cm2

  1. r = 30 ÷ 2 = 15 cm
  2. A = π × r2 = π × 152 = π × 225
  3. ≈ 706.9 cm2
3.A circle has a circumference of 38π cm. Find its radius and its area (leave the area in terms of π).

Answer: r = 19 cm; A = 361π cm2

  1. C = 2πr, so 2πr = 38π
  2. r = 19 cm
  3. A = πr2 = 361π cm2
4.A circle has a radius of 17 cm. Find its area, correct to 1 decimal place.

Answer: 907.9 cm2

  1. A = π × r2 = π × 172 = π × 289
  2. ≈ 907.9 cm2
5.A circle has a radius of 8 cm. Find its area, correct to 1 decimal place.

Answer: 201.1 cm2

  1. A = π × r2 = π × 82 = π × 64
  2. ≈ 201.1 cm2
6.A circle has a circumference of 34π cm. Find its radius and its area (leave the area in terms of π).

Answer: r = 17 cm; A = 289π cm2

  1. C = 2πr, so 2πr = 34π
  2. r = 17 cm
  3. A = πr2 = 289π cm2
7.A circle has a circumference of 32π cm. Find its radius and its area (leave the area in terms of π).

Answer: r = 16 cm; A = 256π cm2

  1. C = 2πr, so 2πr = 32π
  2. r = 16 cm
  3. A = πr2 = 256π cm2
8.A circle has a radius of 6 cm. Find its area, correct to 1 decimal place.

Answer: 113.1 cm2

  1. A = π × r2 = π × 62 = π × 36
  2. ≈ 113.1 cm2
9.A circle has a diameter of 34 cm. Find its area, correct to 1 decimal place.

Answer: 907.9 cm2

  1. r = 34 ÷ 2 = 17 cm
  2. A = π × r2 = π × 172 = π × 289
  3. ≈ 907.9 cm2
10.A circle has a diameter of 26 cm. Find its area, correct to 1 decimal place.

Answer: 530.9 cm2

  1. r = 26 ÷ 2 = 13 cm
  2. A = π × r2 = π × 132 = π × 169
  3. ≈ 530.9 cm2
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