[tex]\textit{volume of a cone}\\\\ V=\cfrac{\pi r^2 h}{3}~~ \begin{cases} r=radius\\ h=height\\[-0.5em] \hrulefill\\ V=\stackrel{doubled}{2V} \end{cases}\implies 2V=\cfrac{\pi r^2 h}{3}\implies V=\cfrac{\pi r^2 h}{3\cdot 2} \\\\\\ V=\cfrac{\pi r^2}{3}\cdot \cfrac{h}{2}\implies V=\cfrac{\pi r^2\left( \frac{h}{2} \right)}{3}\qquad \textit{half the previous "h"}[/tex]
