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7th Grade Circumference and Area of Circles Worksheet — Level 3 — Practice Set 2 — Answers

Answer sheet with worked solutions for the 7th Grade area & perimeter worksheet.

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Success TutoringWorksheetsAnswer sheet7th Grade · Mathematics · Area & Perimeter

7th Grade Circumference and Area of Circles Worksheet — Level 3 — Practice Set 2 — Answers

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

1.A circle has a circumference of 12π cm. Find its radius and its area (leave the area in terms of π).

Answer: r = 6 cm; A = 36π cm2

  1. C = 2πr, so 2πr = 12π
  2. r = 6 cm
  3. A = πr2 = 36π cm2
2.A circle has a circumference of 4π cm. Find its radius and its area (leave the area in terms of π).

Answer: r = 2 cm; A = 4π cm2

  1. C = 2πr, so 2πr = 4π
  2. r = 2 cm
  3. A = πr2 = 4π cm2
3.Find the area of a semicircle with a radius of 20 cm, correct to 1 decimal place.

Answer: 628.3 cm2

  1. A = ½ × π × r2 = ½ × π × 400
  2. ≈ 628.3 cm2
4.A circle has a circumference of 26π cm. Find its radius and its area (leave the area in terms of π).

Answer: r = 13 cm; A = 169π cm2

  1. C = 2πr, so 2πr = 26π
  2. r = 13 cm
  3. A = πr2 = 169π cm2
5.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
6.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
7.A circle has a circumference of 24π cm. Find its radius and its area (leave the area in terms of π).

Answer: r = 12 cm; A = 144π cm2

  1. C = 2πr, so 2πr = 24π
  2. r = 12 cm
  3. A = πr2 = 144π cm2
8.A circle has a radius of 3 cm. Find its area, correct to 1 decimal place.

Answer: 28.3 cm2

  1. A = π × r2 = π × 32 = π × 9
  2. ≈ 28.3 cm2
9.A circle has a radius of 10 cm. Find its area, correct to 1 decimal place.

Answer: 314.2 cm2

  1. A = π × r2 = π × 102 = π × 100
  2. ≈ 314.2 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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