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Year 9 Circumference and Area of Circles Worksheet — Level 1 — Practice Set 3 — Answers

Answer sheet with worked solutions for the Year 9 area & perimeter worksheet.

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Success TutoringWorksheetsAnswer sheetYear 9 · Mathematics · Area & Perimeter

Year 9 Circumference and Area of Circles Worksheet — Level 1 — Practice Set 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 diameter of 24 cm. Find its circumference, correct to 1 decimal place.

Answer: 75.4 cm

  1. C = π × d = π × 24
  2. ≈ 75.4 cm
2.A circle has a radius of 17 cm. Find its circumference, correct to 1 decimal place.

Answer: 106.8 cm

  1. C = 2 × π × r = 2 × π × 17
  2. ≈ 106.8 cm
3.A circle has a diameter of 20 cm. Find its area, correct to 1 decimal place.

Answer: 314.2 cm2

  1. r = 20 ÷ 2 = 10 cm
  2. A = π × r2 = π × 102 = π × 100
  3. ≈ 314.2 cm2
4.A circle has a diameter of 32 cm. What is its radius?

Answer: 16 cm

The radius is half the diameter.

5.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
6.A circle has a diameter of 26 cm. Find its circumference, correct to 1 decimal place.

Answer: 81.7 cm

  1. C = π × d = π × 26
  2. ≈ 81.7 cm
7.A circle has a radius of 6 cm. What is its diameter?

Answer: 12 cm

The diameter is twice the radius.

8.A circle has a radius of 3 cm. What is its diameter?

Answer: 6 cm

The diameter is twice the radius.

9.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
10.A circle has a radius of 4 cm. Find its area, correct to 1 decimal place.

Answer: 50.3 cm2

  1. A = π × r2 = π × 42 = π × 16
  2. ≈ 50.3 cm2
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