Success TutoringWorksheets

9th Grade Circumference and Area of Circles Worksheet — Level 3 — Practice Set 4 — Answers

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

Download answers PDFPrint answersBack to worksheet
Success TutoringWorksheetsAnswer sheet9th Grade · Mathematics · Area & Perimeter

9th Grade Circumference and Area of Circles Worksheet — Level 3 — Practice Set 4 — Answers

Show your work. Use the π button on your calculator and round to 1 decimal place unless told otherwise.

1.A circle has a diameter of 40 cm. Find its area, correct to 1 decimal place.

Answer: 1256.6 cm2

  1. r = 40 ÷ 2 = 20 cm
  2. A = π × r2 = π × 202 = π × 400
  3. ≈ 1256.6 cm2
2.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
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 diameter of 8 cm. Find its area, correct to 1 decimal place.

Answer: 50.3 cm2

  1. r = 8 ÷ 2 = 4 cm
  2. A = π × r2 = π × 42 = π × 16
  3. ≈ 50.3 cm2
5.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
6.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
7.A circle has a radius of 11 cm. Find its area, correct to 1 decimal place.

Answer: 380.1 cm2

  1. A = π × r2 = π × 112 = π × 121
  2. ≈ 380.1 cm2
8.A circle has a circumference of 12π cm. Find its radius and its area (leave the area in terms of π).

Answer: r = 6 cm; A = 36π cm2

  1. C = 2πr, so 2πr = 12π
  2. r = 6 cm
  3. A = πr2 = 36π cm2
9.A circle has a diameter of 30 cm. Find its area, correct to 1 decimal place.

Answer: 706.9 cm2

  1. r = 30 ÷ 2 = 15 cm
  2. A = π × r2 = π × 152 = π × 225
  3. ≈ 706.9 cm2
10.Find the area of a semicircle with a radius of 9 cm, correct to 1 decimal place.

Answer: 127.2 cm2

  1. A = ½ × π × r2 = ½ × π × 81
  2. ≈ 127.2 cm2
Free worksheets at worksheets.successtutoring.com · © Success Tutoring · Free for personal and classroom use

Marking tips

  • Give credit for correct method even when the final answer slips — the working shows where the thinking went right.
  • For open-ended tasks, use the success criteria as a checklist rather than looking for one "right" answer.
  • Celebrate what went well first, then pick one thing to work on next.

Great work. Here's what to try next: