Question

Calculate the length of the circumference of a circle with diameter of 9cm

Answer 1

Hello!

We must use a certain formula to find the circumference of a circle. The formula is:

C = 2 × pi × r

We have the diameter of the circle, so we'll be able to find its radius, since radius is always half the diameter.

r = d ÷ 2

r = 9 ÷ 2

r = 4.5

So, the radius of the circle is 4.5 centimetres. Pi equals approximately 3.14. Substitute:

C = 2 × 3.14 × 4.5

C = 6.28 × 4.5

C = 28.26

ANSWER:

The circumference of the circle is 28.26 centimetres long.