Do you remember how to calculate the perimeter of a circle? Do you know what the special name is for the perimeter of a circle? The formula that we use must be memorised. We can use it to find the perimeter from the radius (or diameter), or to find the radius from the perimeter.

Exercise

Let’s complete exercise 13 from pages 17 and 18 of the core textbook:

Answers

The answers are below:

1. 34.6 cm
2. 25.1 cm
3. 37.7 cm
4. 15.7 cm
5. 28.3 cm
6. 53.4 m
7. 44.6 m
8. 72.3 m
9. 8.48 m
10. 212
11. 400 m
12. 22.6 cm
13. 823 m
14. 643 m