Question

Find the radius of the circle whose area is equal to its circumference?

Answer 1

Let $r$ be the radius of the circle.

This its area $=\pi \times r^2$ and circumference is $2\times \pi \times r$.

Then according to the problem we've,

$\pi \times r^2=2\times \pi \times r$

or, $r=2$.

So the radius of the circle is $2$.