Find the circumference of a circle whose area is 1386 cm².

Let r be the radius of the circle.

The area of circle = 1386 cm²

As we know, the area of the circle = πr²

$⇒ \dfrac{22}{7} \times r^2 = 1386\\[1em] ⇒ r^2 = \dfrac{1386 \times 7}{22}\\[1em] ⇒ r^2 = \dfrac{9702}{22}\\[1em] ⇒ r^2 = 441\\[1em] ⇒ r = \sqrt{441}\\[1em] ⇒ r = 21 \text{ cm}$

Circumference of the circle = 2πr

$= 2 \times \dfrac{22}{7} \times 21\\[1em] = \dfrac{44}{7} \times 21\\[1em] = \dfrac{924}{7}\\[1em] = 132 \text{ cm}$

Hence, the circumference of the circle is 132 cm.