[tex]\bf \textit{area of a circle}\\\\
A=\pi r^2~~
\begin{cases}
r=radius\\
------\\
A=1809.56
\end{cases}\implies 1809.56=\pi r^2
\\\\\\
\cfrac{1809.56}{\pi }=r^2\implies \boxed{\sqrt{\cfrac{1809.56}{\pi }}=r}\\\\
-------------------------------\\\\
\textit{circumference of a circle}\\\\
C=2\pi r\qquad \qquad \implies C=2\pi \left( \boxed{\sqrt{\cfrac{1809.56}{\pi }}} \right)[/tex]
