Question

Find the radius of a circle whose area is 4 times the area of circle having radius 28 cm

Answer 1

Let the radius of the small circle be =r
Let the radius of the big circle be = R
= πr^2 = 4πR^2
= r^2 = 4×14×14
= r = 4×14×14
= r = 2×2×2×7×2×7
= r = 28 c.m.
= Circumference = 2πr
= C = 2× 22/7 × 28
= C = 176 c.m.

Answer 2

Answer:

Given radius =28 cm

We know that, Circumference of the circle i.e, C=2πr

=(2×22/7×28)

=(56×22/7)

=176 cm

176×4 = 704 cm