Question

If the radius of the circle is increased by 100%, by what percent is the area of the circle increased?

Answer 1

let radius =r
$area = \pi {r}^{2}$
new radius=
$\frac{100}{100} \times r + r$
=1×r+r=2r
$new \: area = \pi {(2r)}^{2}$
$= 4\pi {r}^{2}$
so, percentage increase in area=
$\frac{new \: area - orignal \: area}{orignl \: area} \times 100$

Answer 2

hope this image will help you

aryan#