12. In Fig, OACB is a quadrant of a circle with centre O and radius 3.5 cm. If OD = 2 cm, find the area of the
(i) Quadrant OACB
The quadrant OACB is a sector with an angle of 90o and a radius of 3.5 cm.
Thus the area of the quadrant is:-
Hence the area of the quadrant is .