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Circumference

Calculate the circumference of a circle given the radius or diameter, and find the radius given the circumference.

Worked examples

Circumference given radius

Straightforward

Problem

Find the circumference of a circle with radius 66 cm. Give your answer correct to 2 decimal places. Use π≈3.14159\pi \approx 3.14159.

Circumference given diameter

Moderate

Problem

Find the circumference of a circle with diameter 99 m. Give your answer correct to 2 decimal places. Use π≈3.14159\pi \approx 3.14159.

Finding the radius given circumference

Challenging

Problem

A circle has a circumference of 43.9843.98 m. Find the radius correct to 2 decimal places. Use π≈3.14159\pi \approx 3.14159.

Practise

Q1·Straightforward
Find the circumference of a circle with radius 55 cm. Give your answer correct to 2 decimal places. Use π≈3.14159\pi \approx 3.14159.
Q2·Straightforward
Find the circumference of a circle with radius 77 m. Give your answer correct to 2 decimal places. Use π≈3.14159\pi \approx 3.14159.
Q3·Straightforward
Find the circumference of a circle with radius 33 cm. Give your answer correct to 2 decimal places. Use π≈3.14159\pi \approx 3.14159.
Q4·Straightforward
Find the circumference of a circle with radius 1212 m. Give your answer correct to 2 decimal places. Use π≈3.14159\pi \approx 3.14159.
Q5·Moderate
Find the circumference of a circle with diameter 88 cm. Give your answer correct to 2 decimal places. Use π≈3.14159\pi \approx 3.14159.
Q6·Moderate
Find the circumference of a circle with diameter 1111 m. Give your answer correct to 2 decimal places. Use π≈3.14159\pi \approx 3.14159.
Q7·Moderate
Find the circumference of a circle with diameter 1515 cm. Give your answer correct to 2 decimal places. Use π≈3.14159\pi \approx 3.14159.
Q8·Moderate
Find the circumference of a circle with diameter 1818 m. Give your answer correct to 2 decimal places. Use π≈3.14159\pi \approx 3.14159.
Q9·Challenging
A circle has a circumference of 62.8362.83 m. Find the radius correct to 2 decimal places. Use π≈3.14159\pi \approx 3.14159.
Q10·Challenging
A circle has a circumference of 50.2750.27 cm. Find the radius correct to 2 decimal places. Use π≈3.14159\pi \approx 3.14159.
Q11·Challenging
A circle has a circumference of 94.2594.25 m. Find the radius correct to 2 decimal places. Use π≈3.14159\pi \approx 3.14159.
Q12·Challenging
A circle has a circumference of 69.1269.12 cm. Find the radius correct to 2 decimal places. Use π≈3.14159\pi \approx 3.14159.