Question

If the perimeter and the area of a circle are numerically equal, then the diameter of the circle
is....​

Answer 1

$2\pi \: r \: = \pi \: {r}^{2} \\ = > {r}^{2} =2 r \\ = > {r}^{2} -2 r = 0 \\ = > r(r - 2) = 0 \\ r = 2 \\ d = 4$