###### Example2.3.17

The formula for a circle's circumference is \(C=\pi d\text{,}\) where \(C\) stands for circumference, \(d\) stands for diameter, and \(\pi\) is a constant with the value of \(3.1415926\ldots\text{.}\) If a circle's circumference is 12\(\pi\) ft, find this circle's diameter and radius.