In the given figure, O A C B is a quadrant of circle with centre O and radius 3 .5 cm . If O D = 2 cm , find the area of the shaded region.

Since. O A C B is quadrant so it will subtend 90 ° angle at O . Area of quadrant O A C B = 1 4 (area of circle) = 1 4 × 22 7 × 3.5 2 = 1 4 × 22 7 × 7 2 2 = 11 × 7 × 7 2 × 7 × 2 × 2 = 77 8 c m 2 Area of ∆ O B D = 1 2 × O B × O D = 1 2 × 3.5 × 2 = 3.5 c m 2 Area of shaded region = area of quadrant O A C B - area of ∆ O B D = 77 8 - 3.5 = 49 8 c m 2 = 6.125 c m 2 Therefore, area of shaded region = 6.125 c m 2 .

In the given figure, O A C B is a quadrant of circle with centre O and radius 3 .5 cm . If O D = 2 cm , find the area of the Quadrant O A C B .

Since O A C B is quadrant so it will subtend 90 ° angle at O . Area of quadrant O A C B = 1 4 × (area of circle) = 1 4 × 22 7 × 3.5 2 = 1 4 × 22 7 × 7 2 2 = 11 × 7 × 7 2 × 7 × 2 × 2 = 77 8 c m 2