In the adjoining figure, the area enclosed between two concentric circles is 770 cm 2 and the radius of the outer circle is 21 cm. Find the radius of the inner circle.

Question

Philoid · Accepted Answer

Given,

Outer radius of circle, R = 21 cm

Area of enclosed region = 770 cm²

Let the radius of inner circle be r.

Area of enclosed region = Area of outer circle – Area of inner circle

⇒ 770 = πR² – πr²

⇒

⇒ 35(7) = (21)² – r²

⇒ r² = 441 – 245

⇒ r² = 196

⇒ r = 14 cm

In the adjoining figure, the area enclosed between two concentric circles is 770 cm2 and the radius of the outer circle is 21 cm. Find the radius of the inner circle.

In the adjoining figure, the area enclosed between two concentric circles is 770 cm² and the radius of the outer circle is 21 cm. Find the radius of the inner circle.