[tex]\bf \textit{area of a circle}\\\\
A=\pi r^2\quad
\begin{cases}
r=radius\\
-----\\
A=452.16
\end{cases}\implies 452.16=\pi r^2\implies \cfrac{452.16}{\pi }=r^2
\\\\\\
\boxed{\sqrt{\cfrac{452.16}{\pi }}=r}\\\\
-------------------------------\\\\
\textit{circumference of a circle}\\\\
C=2\pi r\qquad \qquad \implies C=2\pi \left( \boxed{\sqrt{\cfrac{452.16}{\pi }}} \right)[/tex]
so, is just that product, recall to use "3.1416 as the value of π".
