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Year 10 Circumference and Area of Circles Worksheet — Level 3 — Practice Set 4 — Answers

Answer sheet with worked solutions for the Year 10 area & perimeter worksheet.

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Success TutoringWorksheetsAnswer sheetYear 10 · Mathematics · Area & Perimeter

Year 10 Circumference and Area of Circles Worksheet — Level 3 — Practice Set 4 — Answers

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

1.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
2.Find the area of a semicircle with a radius of 9 cm, correct to 1 decimal place.

Answer: 127.2 cm2

  1. A = ½ × π × r2 = ½ × π × 81
  2. ≈ 127.2 cm2
3.Find the area of a semicircle with a radius of 4 cm, correct to 1 decimal place.

Answer: 25.1 cm2

  1. A = ½ × π × r2 = ½ × π × 16
  2. ≈ 25.1 cm2
4.A circle has a circumference of 30π cm. Find its radius and its area (leave the area in terms of π).

Answer: r = 15 cm; A = 225π cm2

  1. C = 2πr, so 2πr = 30π
  2. r = 15 cm
  3. A = πr2 = 225π cm2
5.A circle has a circumference of 36π cm. Find its radius and its area (leave the area in terms of π).

Answer: r = 18 cm; A = 324π cm2

  1. C = 2πr, so 2πr = 36π
  2. r = 18 cm
  3. A = πr2 = 324π cm2
6.A circle has a radius of 2 cm. Find its area, correct to 1 decimal place.

Answer: 12.6 cm2

  1. A = π × r2 = π × 22 = π × 4
  2. ≈ 12.6 cm2
7.A circle has a radius of 12 cm. Find its area, correct to 1 decimal place.

Answer: 452.4 cm2

  1. A = π × r2 = π × 122 = π × 144
  2. ≈ 452.4 cm2
8.A circle has a circumference of 16π cm. Find its radius and its area (leave the area in terms of π).

Answer: r = 8 cm; A = 64π cm2

  1. C = 2πr, so 2πr = 16π
  2. r = 8 cm
  3. A = πr2 = 64π cm2
9.A circle has a radius of 18 cm. Find its area, correct to 1 decimal place.

Answer: 1017.9 cm2

  1. A = π × r2 = π × 182 = π × 324
  2. ≈ 1017.9 cm2
10.Find the area of a semicircle with a radius of 7 cm, correct to 1 decimal place.

Answer: 77.0 cm2

  1. A = ½ × π × r2 = ½ × π × 49
  2. ≈ 77.0 cm2
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