Question

se da
cerc
A=9$\pi$cmpatrati
sa se afle lungimea cercului

Answer 1

$A= \pi R^{2} \Rightarrow R= \sqrt{\frac{A}{\pi} }= \sqrt{ \frac{9 \pi}{\pi} } = \sqrt{9} =3 ~(cm). \\ L=2 \pi R=2\pi3=6\pi~(cm).$