Question

In the figure, $OACB$ represents a quadrant of a circle. The radius $OA=3.5cm,OD=2cm$.
The area of the shaded portion is

• A. $613$ ${cm}^2$
• B. $6.13$ ${cm}^2$
• C. $316$ ${cm}^2$
• D. $3.16$ ${cm}^2$

Answer 1

The correct option is B $6.13$ ${cm}^2$

Area of quadrant OACB $=\frac{1}{4}\pi r^2$
$=\frac{1}{4}\times \frac{22}{7}\frac{7}{2}\times \frac{7}{2}$
$=9.63c{m}^2$
Area of $△OAD=\frac{1}{2}\times OA\times OD$
$=\frac{1}{2}\times 3.5\times 2$
$=3.5{cm}^2$
$\therefore$ Area of the shaded portion $=(9.63-3.5)c{m}^2$
$=6.13c{m}^2$