The circumference of a circular ground is $352\, m$. Find the area of the ground (in $m^2$).

In the figure,arcs have been drawn with a radius of $21 \, cm$ each,using vertices $A, B, C,$ and $D$ of quadrilateral $ABCD$ as centers. Find the area of the shaded region in $cm^2$.

If the area of a circle is $154 \, cm^2$,then its perimeter (circumference) is (in $cm$):

$A$ wire fence is to be put up all around a circular ground with diameter $105 \, m$. The length of the fence is $\ldots \ldots \ldots \ldots \, m$.

From a circular metallic sheet with radius $21\, cm$,a regular hexagon of side $21\, cm$ is cut off. Find the area of the remaining sheet. $(\sqrt{3} = 1.73)$ (in $cm^2$)

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