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Year 7 Circumference and Area of Circles Worksheet — Level 3 — Answers

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

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Success TutoringWorksheetsAnswer sheetYear 7 · Mathematics · Area & Perimeter

Year 7 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 8 cm, correct to 1 decimal place.

Answer: 100.5 cm2

  1. A = ½ × π × r2 = ½ × π × 64
  2. ≈ 100.5 cm2
2.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
3.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
4.A circle has a diameter of 12 cm. Find its area, correct to 1 decimal place.

Answer: 113.1 cm2

  1. r = 12 ÷ 2 = 6 cm
  2. A = π × r2 = π × 62 = π × 36
  3. ≈ 113.1 cm2
5.Find the area of a semicircle with a radius of 18 cm, correct to 1 decimal place.

Answer: 508.9 cm2

  1. A = ½ × π × r2 = ½ × π × 324
  2. ≈ 508.9 cm2
6.A circle has a circumference of 10π cm. Find its radius and its area (leave the area in terms of π).

Answer: r = 5 cm; A = 25π cm2

  1. C = 2πr, so 2πr = 10π
  2. r = 5 cm
  3. A = πr2 = 25π 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 diameter of 38 cm. Find its area, correct to 1 decimal place.

Answer: 1134.1 cm2

  1. r = 38 ÷ 2 = 19 cm
  2. A = π × r2 = π × 192 = π × 361
  3. ≈ 1134.1 cm2
9.A circle has a circumference of 22π cm. Find its radius and its area (leave the area in terms of π).

Answer: r = 11 cm; A = 121π cm2

  1. C = 2πr, so 2πr = 22π
  2. r = 11 cm
  3. A = πr2 = 121π cm2
10.A circle has a circumference of 8π cm. Find its radius and its area (leave the area in terms of π).

Answer: r = 4 cm; A = 16π cm2

  1. C = 2πr, so 2πr = 8π
  2. r = 4 cm
  3. A = πr2 = 16π cm2
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