Question

In figure, AB and CD are two diameters of a circle (with centre O) perpendicular to each other and OD is the diameter of the smaller circle. If OA = 7 cm, find the area of the shaded region. [4 MARKS]

Answer 1

Concept: 1 Mark
Application: 3 Marks

OD is diameter of smaller circle.

Area of the smaller circle
$=\pi \times {3.5}^2=38.49c{m}^2$

Area of $\Delta ABC=0.5\times \left(14\right)\left(7\right)=49c{m}^2$

Area of semi-circle $=0.5\pi \left(7\right)\left(7\right)=76.97c{m}^2$

Area of shaded portion in semi-circle $=76.97-49=27.97c{m}^2$

Total required area $=38.49+27.97=66.46c{m}^2$