[tex]\bf \textit{volume of a cone}\\\\
V=\cfrac{\pi r^2 h}{3}\quad
\begin{cases}
r=radius\\
h=height\\
------\\
h=7\\
V=288
\end{cases}\implies 288=\cfrac{\pi \cdot r^2\cdot 7}{3}
\\\\\\
\cfrac{288\cdot 3}{7\pi }=r^2\implies \sqrt{\cfrac{288\cdot 3}{7\pi }}=r[/tex]