Question

Find the area between two concentric circles whose radii are 4m and 2m.
2
[ 37.7 A m  ]

Answer 1

Let the radii of the outer circle and inner circle be r2 and r1.

here, r2 = 4

r1 = 2

Answer 2

Given:

Two concentric circles of radii 4m and 2m.

To find:

The area between the two concentric circles.

Solution:

The area between two concentric circles whose radii are 4m and 2m is 37.699m².

Let the outer radius be $R_1 = 4m$ and the inner radius be $R_2 = 2m.$

According to the diagram, the area between two concentric circles will be =

Area of the outer circle - Area of the inner circle.

$Area =\pi r_{2}^{2}-\pi r_{1}^{2}\\\\=\pi\left(r_{2}^{2}-r_{1}^{2}\right) \\\\ =\pi\left(r_{2}-r_{1}\right)\left(r_{2}+r_{1}\right) \\\\ =\pi(4-2)(4+2)\\\\=\pi \times 2 \times 6 = 12 \pi = 37.699m^2.$

Therefore, the area is 37.699m².