TeX Quellcode:

\begin{array}{rclcl} 615{,}75 &=& 4\pi r^2 &\vert& :\left(4\pi\right) \cr \dfrac{615{,}75}{4\pi} &=& r^2 &\vert& \sqrt{} \cr r &=& \sqrt{\dfrac{615{,}75}{4\pi}} \cr &\approx& 7{,}00 \, cm\end{array}