[tex]\bf \textit{surface area of a sphere}\\\\
A=4\pi r^2\qquad
\begin{cases}
r=radius=\frac{diameter}{2}\\
diameter=2r\\
----------\\
A=45,239
\end{cases}\implies 45,239=4\pi r^2[/tex]
solve for "r", to see what the radius is
keep in mind that, the diameter is just "2r"
