Question

In the given figure, the sectors of two concentric circles of radii 7 cm and 3.5 cm are shown. Find the area of the shaded region.

Answer 1

Area of the shaded region = (Area of the sector with r =7 cm and θ -30°) - (Area of the sector with r = 3.5 cm and θ = 30°)

`=|(22/7xx7xx7xx30/360) - (22/7xx3.5xx3.5xx30/360)|"cm"^2`

`=(77/6-77/24)"cm"^2`

`=77/8 "cm"^2`

= 9.625 cm²