Respuesta :

[tex]\bf \begin{cases} \textit{area of a circle}=\pi r^2 \\ \quad \\ circumference=2\pi r \end{cases} \\ \quad \\ 12.56=\pi r^2\implies \cfrac{12.56}{\pi }=r^2\implies \sqrt{\cfrac{12.56}{\pi }}=\boxed{r} \\ \quad \\ thus \\ \quad \\ circumference=2\pi \boxed{r}\implies 2\pi \boxed{\sqrt{\cfrac{12.56}{\pi }}}[/tex]

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