Question

Question 30

If the radius of a circle is increased to twice its original length, how much will the area of the circle increase?

(a) 1.4 times
(b) 2 times
(c) 3 times
(d) 4 times

Answer 1

Let r be the radius of the circle.
$\therefore$ Area of circle $=\pi r^2$
If the radius is increased to twice its original length, then radius will be 2r.
Now, area of new circle $=\pi (2r{)}^2=4\pi r^2=4$ times of original area
Hence, the area of the circle will be increased to 4 times.