\begin{eqnarray*} 	V_{\text{cono truncado}} &=& V_{\text{cono grande}} - V_{\text{cono chico}} 	\\ 		&=& \frac{1}{3}\,\pi R^{2}\cdot (H + h) - \frac{1}{3}\,\pi r^{2}\,H				\\ 		&=& \frac{1}{3}\,\pi R^{2}\,H + \frac{1}{3}\,\pi R^{2}\,h  - \frac{1}{3}\,\pi r^{2}\,H				\\ 		&=& \frac{1}{3}\,\pi\,H\cdot\left(R^{2} - r^2\right) + \frac{1}{3}\,\pi R^{2}\,h  \end{eqnarray*}