In this worksheet, we will practice finding the circumference of a circle using the formula 2πr.

**Q5: **

The circumference of a circle is a function of its diameter represented by the equation . If the diameter is the input and the circumference is the output, calculate the circumference when the diameter is 5.

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**Q7: **

If the radius of a circle equals 13.8 cm, find the length of its longest chord.

**Q8: **

Find the circumference of a circle whose radius is 12.4 cm. Give your answer to the nearest centimetre.

**Q9: **

Using to approximate , what is the difference in circumference between a circle of radius 77 cm and one of radius 63 cm?

**Q10: **

Using to approximate , what is the difference in circumference between a circle of diameter 63 cm and one of diameter 49 cm?

**Q11: **

Using 3.14 to approximate , what is the difference in circumference between a circle of diameter 100 cm and one of radius 15 cm?

**Q12: **

Work out the circumference of the circle, giving your answer accurate to two decimal places.

**Q13: **

Work out the circumference of the circle, giving your answer accurate to two decimal places.

**Q14: **

Work out the circumference of the circle, giving your answer accurate to two decimal places.

**Q15: **

The two circles shown in the diagram are concentric. Work out the circumference of the larger circle, giving your answer in terms of .

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**Q16: **

What is the radius of a circle with circumference cm?

**Q17: **

Using 3.14 to approximate , determine the number of turns that a wheel of diameter 55 cm makes in rolling a distance of 345.4 cm.

**Q18: **

Determine the perimeter of the figure, using 3.14 to approximate .

**Q19: **

Use 3.14 to approximate and calculate the circumference of the circle.

**Q20: **

What is the formula for the circumference of a circle with radius ?

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**Q21: **

Work out the circumference of a circle with a diameter of 10 inches, giving your answer to two decimal places.

**Q22: **

The formula for the circumference of a circle is . Find the circumference of a circle with a diameter of 12 in. Give your answer in terms of , knowing that the diameter is equal to .

- A in
- B in
- C in
- D in

**Q23: **

The formula for the circumference of a circle is . Rearrange this formula to make the subject.

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**Q24: **

Find, to the nearest hundredth, the circumference of a circle of diameter 55.5 cm.

**Q25: **

The length of the longest chord in a circle is 40.3 cm. Find its circumference. You may approximate by 3.14.