In the adjoining diagram, $\overline{ AB }$ and $\overline{ CD }$ are diameters of $\odot( O , 7\, cm )$ perpendicular to each other. A circle is drawn with diameter $\overline{ OD }$. Find the area of the shaded region. (in $cm^2$)

Find the area of a sector of a circle of radius $28 \,cm$ and central angle $45^{\circ} .$ (in $cm ^{2}$)

The circumference of a circle with radius $8.4\,cm$ is $\ldots \ldots \ldots \ldots cm$.

In a circle with radius $42\,cm ,$ an arc subtends an angle of measure $120$ at the centre. Then, the area of the minor sector formed by that arc is $\ldots \ldots \ldots . . cm ^{2}$.

Sides of a triangular field are $15\, m , 16 \,m$ and $17\, m$. With the three corners of the field a cow, a buffalo and a horse are tied separately with ropes of length $7 \,m$ each to graze in the field. Find the area of the field which cannot be grazed by the three animals.

In a circle with radius $42\, cm$, a minor arc subtends an angle of measure $60$ at the centre. Find the area of the minor sector and the minor segment corresponding to this arc. $(\sqrt{3}=1.73)$