1. Circumference of a circle
Perimeter of a circle
Saturday, 06 April 2019

2. Example
Taking the piece of string measure the circumference of the circular face on the tin.
With your ruler now measure the diameter.
Work out
𝐶𝑖𝑟𝑐𝑢𝑚𝑓𝑒𝑟𝑒𝑛𝑐𝑒 𝑜𝑓 𝑓𝑎𝑐𝑒 𝐷𝑖𝑎𝑚𝑒𝑡𝑒𝑟 𝑜𝑓 𝑐𝑖𝑟𝑐𝑙𝑒

3. 𝐶𝑖𝑟𝑐𝑢𝑚𝑓𝑒𝑟𝑒𝑛𝑐𝑒=𝜋𝐷 Diameter Example
Work out the circumference of a circle whose diameter is 8cm, giving your answer correct to 2 decimal places.
C=𝜋𝐷
𝐶=𝜋 ×8
𝐶=25.13 𝑐𝑚

4. Example
Work out the circumference for each of the following circles, giving your answers correct to 1 decimal place.
(i)
(ii)
3.6m
12cm

5. (iii)
(iv)
20cm
13cm

6. Example
Work out the perimeter of the semicircle drawn below.
Give your answer correct to 2 decimal places.
15cm

7. Example
Given that the Circumference of a circle is 100cm, work out the diameter of this Circle.