[tex]\bf \textit{volume of a cylinder}\\\\ V=\pi r^2 h~~ \begin{cases} r=radius\\ h=height\\[-0.5em] \hrulefill\\ V=360\pi \\ h=15 \end{cases}\implies 360\pi =\pi r^2(15)\implies \cfrac{360\pi }{15\pi }=r^2 \\\\\\ 24=r^2\implies \sqrt{24}=r~\hfill \stackrel{diameter = 2r}{2\sqrt{24}~~\approx~~ 9.80}[/tex]
