Question

The area of a circle is $1386$ sq. cm, find its circumference.

Answer 1

Area of circle $=1386c{m}^2$

$\therefore \pi r^2=1386$ where $r$ is the radius of the circle.

$\Rightarrow \frac{22}{7}{r}^2=1386$

$\Rightarrow r^2=1386\times \frac{7}{22}$

$\Rightarrow r^2=441$

$\Rightarrow r=\sqrt{441}$

$\Rightarrow r=21cm$

$\therefore$ Circumference $=2\pi r$

$=2\times \frac{22}{7}\times 21$

$=132cm$