Question

Find the area of a ring whose outer and inner radii are respectively 23 cm and 12 cm.

Answer 1

Let r₁ cm and r₂ cm be the radii of the outer and inner boundaries of the ring, respectively.
We have:

r1 = 23 cm 

r2 = 12 cm

Now,

Area of the outer ring `= π"r"_1^2`

`=22/7xx23xx23`

=  1662.57 cm² 

Area of the inner ring `= π"r"_2^2`

`= 22/7xx12xx122`

= 452.57 cm² 

Area of the ring = Area of the outer ring - Area of the inner ring

= 1662.57 - 452.57

= 1210 cm²