Respuesta :

[tex]\bf \textit{surface area of a sphere}\\\\ A=4\pi r^2\qquad \begin{cases} r=radius\\ -----\\ A=12.56 \end{cases}\implies 12.56=4\pi r^2 \\\\\\ \cfrac{12.56}{4\pi }=r^2\implies \sqrt{\cfrac{12.56}{4\pi }}=r[/tex]