Question

In the given figure ABCD is a rectangle of dimensions 21 cm $\times$ 14 cm. A semicircle is drawn with BC as diameter. Find the area and the perimeter of the shaded region in the figure.

Answer 1

Area of shaded region = Area of rectangle - Area of semi circle
$=l\times b-\frac{1}{2}\pi r^2=21\times 14-\frac{1}{2}\times \frac{22}{7}\times 7\times 7=294-77=217{\text{cm}}^2$
Perimeter of shaded region = $2l+b+\pi r=2\times 21+14+\frac{22}{7}\times 7=42+14+22=78\text{cm}$