Question

The different between the rades of tuo circles is
Fom and difference between they areas is 10785 q
cm find the radius of the smaller circle
(a) 14
(b) 21
​

Answer 1

Step-by-step explanation:

Let the radius of the smaller circle be r cm

Then, radius of bigger circle =(r+7)cm

Given, π(r+7)

2

−π(r)

2

=1078

⇒ π(r

2

+14r+49)−πr

2

=1078

⇒πr

2

+14πr+49π−πr

2

−1078

⇒14×

7

22

×r+49×

7

22

=1078

⇒44r+154=1078

⇒44r=924

⇒r=21cm