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  

\[\pi r^2 = 2\pi r\]
\[ \Rightarrow \pi r^2 - 2\pi r = 0\]
\[ \Rightarrow \pi r\left( r - 2 \right) = 0\]
\[ \Rightarrow r = 0 or r = 2\]
Since radius cannot be equal to 0 so, r = 2