Question

Question 36

If the radius of a circle is tripled, the area becomes

(a) 9 times
(b) 3 times
(c) 6 times
(d) 30 times

Answer 1

Let 'r' be the radius of a circle.
$\because$ Area of circle $=\pi r^2$
If radius is tripled, then new radius will be 3r.
$\therefore$ Area of new circle $=\pi (3r{)}^2=9\pi r^2=9$ times of original
Hence, the area of a circle becomes 9 times of the original area.