Question

the radius of circle is increase by 20%, then by how much percent its area would increase?

Answer 1

Answer:

Let the radius of original circle =r

∴ Area of original circle =πr

2

But, the radius of the circle is increased by 20%

∴ Radius of new circle R=

100

20r

+r=1.2r

Area of new circle =πR

2

=π(1.2r)

2

=1.44πr

2

Increased area =1.44πr

2

−πr

2

=0.44πr

2

Percentage increase in area =

πr

2

0.44πr

2

×100=44%