Question

OACB is a quadrant of a circle with centre O and radius 7 cm. If OD = 4cm, then find the area of shaded region. [3 MARKS]

Answer 1

Concept: 1.5 Marks
Application: 1.5 Marks

Area of quadrant OACB $=\frac{90}{360}\pi \times 7^2=\frac{77}{2}$

Area of $\Delta OAD=\frac{1}{2}\times 7\times 4$

Area of shaded region = Area of quadrant OACB - area of $\Delta OAD$

$=\frac{77}{2}-\frac{1}{2}\times 7\times 4$

$=24.5c{m}^2$