Let ABC be a cone. A frustum DECB is cut by a plane parallel to its base.

Let r_{1} and r_{2} be the radii of the ends of the frustum of the cone and h be the height of the frustum of the cone.

In ΔABG and ΔADF, DF||BG

∴ ΔABG ∼ ΔADF

Volume of frustum of cone = Volume of cone ABC − Volume of cone ADE