Question

The radius of a circle is 5 m. Find the circumference of the circle whose area is 49 times the area of the given circle.

Answer 1

Area of the circle having radius 5 m is

A = π × (5)² 

= 25 π m²

Let r be the radius of the circle whose area is 49 times of the given circle.

π r² = 49 × (π x 5²)

r² = (7 × 5)²

r = 35 m

Hence circumference of the circle

circumference = 2πr

circumference = 2 × `22/7`× 35

circumference = 220 m