## Precalculus: Concepts Through Functions, A Unit Circle Approach to Trigonometry (3rd Edition)

$V(r)=2\pi r^3$
We know that the height is twice the radius, so $h=2r$ We know that the volume is given by: $V=\pi r^2 h$ Therefore, the composite function will be: $V(r)=\pi r^2 h=\pi (r^2) (2r)=2\pi r^3$