C (r), the circumference of a tire, is based on the radius, r. What is an appropriate domain for the function?

Given:

C (r) is the circumference of a tire

with radius, r

The appropriate domain for the function is needed.

First, we set-up the equation for the circumference of a circle, assuming that the tire is a perfect circle:

C (r) = 2 * pi * r

the domain of the function is all values of r greater than zero. It can also be written as [1, infinity)