In Fig., OACB is a quadrant of a circle with centre O and radius 3.5cm. If OD=2cm, find the area of the (i) quadrant OACB, (ii) shaded region.

(i)Area of quadrant OACB=Area of Circle/4 = π × r²/4 = (1/4) × (22/7) × 3.5 × 3.5 = 9.625cm²
(ii)Area of the shaded region=Area of Quadrant - Area of ΔBDO = 9.625 - (1/2 × 3.5 × 2) = 6.125cm²