Question

What is an equation that relates the circumference of a circle as a function of its diameter?

Answer 1

`c=pi*d`,
Where:
`c` is the circumference of the circle, and
`d` is the diameter of the circle.

Explanation:

This is a static relationship, meaning that no matter how large or small the circle is, the circumference will always be `pi` times a large as the diameter.

For example:

Say you have a circle with a diameter of `6` inches:

The circumference will be `pi` times that, or `6pi` inches.
(`18.849555`... inches)

If you're given the radius, all you have to do is double the radius to get the corresponding diameter. Or, you can go straight from radius to circumference with the equation

`c=2pir`,
Where:
`c` is the circumference of the circle, and
`r` is the radius of the circle.

Hopefully this helped!