Question

If the numerical value of the area of a circle is equal to the numerical value of its circumference , find its radius.

Answer 1

Given that area of the circle = circumference  

$$\pi r^2=2\pi r$$
$$\Rightarrow \pi r^2-2\pi r=0$$
$$\Rightarrow \pi r(r-2)=0$$
$$\Rightarrow r=0orr=2$$
Since radius cannot be equal to 0 so, r = 2