Question

If the area of a circle measures 4π cm2, what is the circumference of the circle in terms of π? A) 4π cm B) 8π cm C) 12π cm D) 16π cm

Answer 1

$\bf \textit{area of a circle}\\\\ A=\pi r^2~~ \begin{cases} r=radius\\ -----\\ A=4\pi \end{cases}\implies 4\pi =\pi r^2\implies \cfrac{4\pi }{\pi }=r^2 \\\\\\ 4=r^2\implies \sqrt{4}=r\implies \boxed{2=r} \\\\\\ \textit{circumference of a circle}\\\\ C=2\pi r\qquad \qquad \implies C=2\pi\left( \boxed{2} \right)\implies C=4\pi$