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Find the Circumference of a Circle

In this worksheet, students will use formulae to calculate the circumferences of circles given their radii.

'Find the Circumference of a Circle' worksheet

Key stage:  KS 3

Year:  Year 8 Maths worksheets

Curriculum topic:   Geometry and Measures

Curriculum subtopic:   Solve Problems Involving Perimeters and Areas of 2D Shapes

Difficulty level:  

Worksheet Overview

This activity is about finding the circumferences of circles.

The circumference of a circle is its perimeter or the distance around its edge.


You need to learn these two important formulae for a circle of radius, r or diameter, d:


Circumference of a circle = 2πr

Circumference of a circle = πd


This is because the diameter of a circle is two times the length of the radius: 2 x r = d


The value of π (pi) is 3.142.... but is an infinite number, so the best way to do any calculations with pi is to use a scientific calculator that has a special π  button.


the circumference of a circlethe diameter of a circle


Example 1

Find the circumference of a circle of radius 6 cm.



Circumference = 2 × π × r = 2 × π × 6 = 12 × π = 37.7 cm  (1 decimal place)



Example 2

Find the circumference of a circle of diameter 6 cm.



Circumference = π × d = π × 6 = 18.8 cm  (1 decimal place)


Use a scientific calculator to work out your answer because you can have a more accurate number for pi  (π ).  

If you don't have one in the house, you can access one online.


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