Question

Ramesh circular sheet of diameter 21 CM a circle of diameter 7 centimetre is removed find the area of remaining sheet​

Answer 1

Given : Diameter of Outer circular sheet = 21 cm

⇒Diameter of Inner circular sheet = 7 cm

⇒We know Radius = Diameter/2

⇒so, Radius of Outer circular sheet , R = 21/2 = 10.5 cm

⇒Radius of inner circular sheet, r = 7/2 = 3.5 cm

⇒Now, When the inner circle of radius 3 .5 cm is removed, then

⇒Then, Remaining area = πR² ― πr²

⇒Remaining area = π(10.5)² ― π(3.5)²

⇒π × 10.5 × 10.5 ― π × 3.5 × 3.5

⇒3.14 × 110.25 × 3.14 × 12.25

⇒346.185 ― 38.465

⇒307.72 cm²

Answer 2

Answer:

circumference =3 area

2πr = 3π r^2

2r = 3r^2

2= 3r

3/2= r