A cow is tied with a rope of length $14\, m$ at the corner of a rectangular field of dimensions $20 \,m \times 16 \,m$. Find the area of the field in which the cow can graze. (in $m ^{2}$)

Four circular cardboard pieces of radii $7\, cm$ are placed on a paper in such a way that each piece touches other two pieces. Find the area of the portion enclosed between these pieces. (in $cm^2$)

The area of the square that can be inscribed in a circle of radius $8 cm$ is (in $cm ^{2}$)

In a circle with radius $50\, cm$, the area of the sector formed by a $20 \,cm$ long arc is $\ldots \ldots \ldots cm ^{2}$

In $\odot( O , r) \overline{ OA }$ and $ \overline{ OB }$ are two radii perpendicular to each other. If the, perimeter of the minor sector formed by those radii is $20\,cm ,$ then $r=\ldots \ldots \ldots . . . cm$

In $\odot( O , r),$ the length of minor $\widehat{ ACB }$ is one-eighth of the circumference of the circle. Then, the measure of the angle subtended at the centre by that arc is $\ldots \ldots \ldots \ldots$