A cone by two methods Verify that the volume of a right circular cone with a base radius of $r$ and a height of $h$ is $\pi r^{2} h / 3 .$ Use the region bounded by the line $y=r x / h$, the $x$ -axis, and the line $x=h,$ where the region is rotated around the $x$ -axis. Then (a) use the disk method and integrate with respect to $x,$ and (b) use the shell method and integrate with respect to $y$