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Year 8 Circumference and Area of Circles Worksheet — Level 3 — Answers

Answer sheet with worked solutions for the Year 8 area & perimeter worksheet.

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Success TutoringWorksheetsAnswer sheetYear 8 · Mathematics · Area & Perimeter

Year 8 Circumference and Area of Circles Worksheet — Level 3 — 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 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
2.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
3.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
4.A circle has a radius of 19 cm. Find its area, correct to 1 decimal place.

Answer: 1134.1 cm2

  1. A = π × r2 = π × 192 = π × 361
  2. ≈ 1134.1 cm2
5.Find the area of a semicircle with a radius of 12 cm, correct to 1 decimal place.

Answer: 226.2 cm2

  1. A = ½ × π × r2 = ½ × π × 144
  2. ≈ 226.2 cm2
6.A circle has a diameter of 28 cm. Find its area, correct to 1 decimal place.

Answer: 615.8 cm2

  1. r = 28 ÷ 2 = 14 cm
  2. A = π × r2 = π × 142 = π × 196
  3. ≈ 615.8 cm2
7.A circle has a diameter of 14 cm. Find its area, correct to 1 decimal place.

Answer: 153.9 cm2

  1. r = 14 ÷ 2 = 7 cm
  2. A = π × r2 = π × 72 = π × 49
  3. ≈ 153.9 cm2
8.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
9.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
10.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
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