Question

In the figure, $PQSR$ represents a flower bed. If $OP=21m$ and $OR=14m$, find the area of the shaded portion.

Answer 1

Given: $OP=21m$ and $OR=14m$
Area of the flower bed $=$ Area of the quadrant OQP $-$ Area of the quadrant $OSR$
$=\frac{1}{4}\pi \times O{P}^2-\frac{1}{4}\pi \times O{R}^2$
$=\frac{1}{4}\times \pi \times {21}^2-\frac{1}{4}\times \pi \times {14}^2$
$=\frac{1}{4}\times \pi \times ({21}^2-{14}^2)$
$=\frac{1}{4}\times \frac{22}{7}\times (21+14)\times (21-14)$
$\therefore$ Area of the flower bed $=\frac{1}{4}\times \frac{22}{7}\times 35\times 7=192.5m^2$.