check the picture below.
[tex] \bf \textit{surface area of a cone}\\\\
SA=\pi r\stackrel{slant~height}{\sqrt{r^2+h^2}}+\pi r^2~~
\begin{cases}
r=radius\\
h=height\\
-----\\
r=8\\
\sqrt{r^2+h^2}=15
\end{cases}
\\\\\\
SA=\pi (8)(15)+\pi (8)^2\implies SA=120\pi +64\pi \implies SA=184\pi [/tex]
