if its diameter is 8 cm, then its radius is half that, or 4 cm.
[tex]\bf \textit{volume of a cone}\\\\ V=\cfrac{\pi r^2 h}{3}~~ \begin{cases} r=radius\\ h=height\\ \cline{1-1} r=4\\ h=13 \end{cases}\implies V=\cfrac{\pi (4)^2(13)}{2} \\\\\\ V=104\pi \implies \stackrel{\pi =3.14}{V=326.7}[/tex]
