Question

Rewrite the formula for the circumference of a circle C=2xpix r in terms of its diameter d. Show your work.

Answer 1

diameter = 2·radius

С = 2·π·r ⇒ С = π·d

Answer 2

Hi there!

The answer is

`circumference \: = d\pi`
In this formula d represents the diameter.

We know that 2 times the radius equals the diameter, hence

`2r = d`

Therefore we can replace the 2r in the original formula by d, and then we get the following:

`circumference = 2\pi \: r = 2r\pi = d\pi`