[tex]\bf \textit{area of a circle}\\\\
A=\pi r^2\quad
\begin{cases}
r=radius\\
------\\
A=530.66
\end{cases}\implies 530.66=\pi r^2
\\\\\\
\cfrac{530.66}{\pi }=r^2\implies \sqrt{\cfrac{530.66}{\pi }}=r
\\\\\\
\textit{circumference of a circle}\\\\
C=2\pi r\qquad \implies C=2\pi \left( \sqrt{\cfrac{530.66}{\pi }} \right)[/tex]
