Circles

finding the area and perimeter of circles

In your maths exam you may be asked to find the area or circumference of a circle. This is normally on your calculator paper of your maths exam. Check out the formulae page if you can't remember how to work out the area or circumference of a circle.

Example Question

A circular pond has a radius of 8 metres.

a) Find the area of the pond.
b) Find the circumference of the pond.

Give your answers to one decimal place.

Solution

a) The area of the pond is given by the formula A = πr2. Where r is the radius of the pond.

So area of pond = π x 82 = 201.0619298 = 201 m2 (1 decimal place.)

b) The circumference of the pond is given by the formula C = πD. Where D is the diameter of the pond.
Remember: The diameter is twice the size of the radius = 8 x 2 = 16 m

So the circumference of the pond =  π x 16 = 50.26548246 = 50.3 m (1 decimal place.)

Test Yourself!

Find the area of the circle below. Give your answer to 1 decimal place.

m2

Find the circumference of the circle below. Give your answer to 1 decimal place.

cm

Practice GCSE questions:

Grade C question