Calculate the circumference of a circle whose area is $1386\mathrm{sq}·\mathrm{cm}$.

We know that,

Area of a circle$=\pi {\mathrm{r}}^2$

According to the given data and by substituting the values we get,

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

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

$\Rightarrow r^2=441 {\text{cm}}^2$

$\Rightarrow r=21 \text{cm}$

Now, the circumference of a circle $=2\mathrm{\pi r}$

Therefore, by substituting the value of r, we get,

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

$=132 \mathrm{cm}$