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

Given:

The area of a circle = 1386 sq. cm

Let r be the radius of the circle.

As we know, the area of the circle = πr²

$⇒ \dfrac{22}{7} \times r^2 = 1386\\[1em] ⇒ r^2 = \dfrac{1386 \times 7}{22}\\[1em] ⇒ r^2 = \dfrac{9,702}{22}\\[1em] ⇒ r^2 = 441\\[1em] ⇒ r = \sqrt{441}\\[1em] ⇒ r = 21 \text{ cm}$

Circumference of the circle = 2πr

$= 2 \times \dfrac{22}{7} \times 21\\[1em] = \dfrac{44}{7} \times 21\\[1em] = \dfrac{324}{7}\\[1em] = 132 \text{ cm}$

Hence, the circumference of the circle is 132 cm.