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Year 8 Circumference and Area of Circles Worksheet — Level 3 — Practice Set 2 — 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 — Practice Set 2 — 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 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
2.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
3.Find the area of a semicircle with a radius of 10 cm, correct to 1 decimal place.

Answer: 157.1 cm2

  1. A = ½ × π × r2 = ½ × π × 100
  2. ≈ 157.1 cm2
4.A circle has a diameter of 32 cm. Find its area, correct to 1 decimal place.

Answer: 804.2 cm2

  1. r = 32 ÷ 2 = 16 cm
  2. A = π × r2 = π × 162 = π × 256
  3. ≈ 804.2 cm2
5.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
6.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
7.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
8.A circle has a circumference of 14π cm. Find its radius and its area (leave the area in terms of π).

Answer: r = 7 cm; A = 49π cm2

  1. C = 2πr, so 2πr = 14π
  2. r = 7 cm
  3. A = πr2 = 49π cm2
9.Find the area of a semicircle with a radius of 19 cm, correct to 1 decimal place.

Answer: 567.1 cm2

  1. A = ½ × π × r2 = ½ × π × 361
  2. ≈ 567.1 cm2
10.A circle has a circumference of 6π cm. Find its radius and its area (leave the area in terms of π).

Answer: r = 3 cm; A = 9π cm2

  1. C = 2πr, so 2πr = 6π
  2. r = 3 cm
  3. A = πr2 = 9π cm2
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