Question

What is the formula for finding the diameter of a circle if you know the circumference?

Answer 1

circumference =
$2\pi \: r$
r = radius
diameter of a circle = 2r

Answer 2

Let the circumference of a circle be C, and the diameter of a circle be d.$C=\pi\times d$
Rearranging to find the diameter in terms of the circumference, we get the formula:
$d=\frac{C}{\pi}$