Question

Find the circumference of the circle that is within a square if the area of the square is $81c{m}^2$.
$(Take\pi =\frac{22}{7})$.

• A. $7\frac{2}{7}cm$
• B. $14\frac{2}{7}cm$
• C. $28\frac{2}{7}cm$
• D. $63\frac{9}{14}cm$

Answer 1

Answer: (C)

$28\frac{2}{7}cm$

Area of square $=81c{m}^2$
$Side\times Side=81c{m}^2\Rightarrow Side=9cm$
Now, diameter of circle $=$ side of square $=9cm$
$\therefore$ Radius $\left(r\right)$ of circle $=\frac{9}{2}cm$.
So, circumference of circle $=2\pi r$
$=(2\times \frac{22}{7}\times \frac{9}{2})cm=28\frac{2}{7}cm$.