A square $OABC$ is inscribed in a quadrant $OPBQ$ of a circle as shown in the figure, if $OA=14 \mathrm{cm}$ the area of shaded region is $k {\mathrm{cm}}^2$. Find the value of $k$.

 

 

In the figure, $AOBCA$ represents the quadrant of a circle of radius $3.5 \mathrm{cm}$. The area of shaded portion is $k {\mathrm{cm}}^2$. (Take $\pi =\frac{22}{7}$). Find the value of $k$.

In the figure, $ABDC$ represents a flower bed. If $OA=21 \mathrm{m}$ and $OC=14 \mathrm{m}$. The area of flower bed is $k {\mathrm{cm}}^2$. Find the value of $k$.

In the figure, $ABC$ is a right-angled triangle at $A$. Semicircles are drawn on $AB, AC$ and $BC$ as diameters. It is given that $AB=3 \mathrm{cm}$ and $AC=4 \mathrm{cm}$. If the area of the shaded region is $k {\mathrm{cm}}^2$, then find the value of $k$.

A drain cover is made from a circular metal plate of radius $14 \mathrm{cm}$ having $21$ holes each of diameter $0.5 \mathrm{cm}$. If the area of the remaining plate is $k {\mathrm{cm}}^2$, then find the value of $k$.

Find the area of the segment $APB$ shown in figure, if radius of the circle is $21 \mathrm{cm}$ and $\angle AOB=120°$.