Question

If circumference and area of a circle are numerically equal, how long is its diameter?

• A. 2
• B. 8
• C. $2\pi$
• D. 4

Answer 1

The correct option is D

4

Given: Area of the circle = Circumference of the circle
$\Rightarrow$ $\pi r^2=2\pi r$ ,where $r$ is the radius of the circle.
$\Rightarrow$ $r^2=2r$
$\Rightarrow$ $r=2$
$\Rightarrow$ $2r=4$
$\therefore$ The diameter of the given circle is 4 units long.