$A$ 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 $m^2$)

The length of the minute hand of a clock is $5\, cm$. Find the area swept by the minute hand during the time period $6:05\, a.m.$ and $6:40\, a.m.$ (in $cm^2$).

$A$ calf is tied with a rope of length $6 \,m$ at the corner of a square grassy lawn of side $20 \,m$. If the length of the rope is increased by $5.5 \,m$,find the increase in area of the grassy lawn in which the calf can graze. (in $m^2$)

In a circle with radius $r$,the area of a sector formed by an arc of length $l$ is.........

Three circles each of radius $3.5\, cm$ are drawn in such a way that each of them touches the other two. Find the area enclosed between these circles. (in $cm^{2}$)

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