If the radius of a circle is$\sqrt{140 }\mathrm{m}$, then find the area of a circle.

Given, 

The radius of a circle (r) is $\sqrt{140}\mathrm{m}$

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

$=\mathrm{\pi }{\left(\sqrt{140}\right)}^2$

$=\frac{22}{7}\times 140=440 {\mathrm{m}}^2$

Therefore, the area of a circle is $440 {\mathrm{m}}^2$