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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.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
2.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
3.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
4.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
5.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
6.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
7.A circle has a circumference of 28π cm. Find its radius and its area (leave the area in terms of π).

Answer: r = 14 cm; A = 196π cm2

  1. C = 2πr, so 2πr = 28π
  2. r = 14 cm
  3. A = πr2 = 196π 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 circumference of 18π cm. Find its radius and its area (leave the area in terms of π).

Answer: r = 9 cm; A = 81π cm2

  1. C = 2πr, so 2πr = 18π
  2. r = 9 cm
  3. A = πr2 = 81π cm2
10.A circle has a diameter of 16 cm. Find its area, correct to 1 decimal place.

Answer: 201.1 cm2

  1. r = 16 ÷ 2 = 8 cm
  2. A = π × r2 = π × 82 = π × 64
  3. ≈ 201.1 cm2
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