Find the area of a sector of a circle of radius $21 \, cm$ and central angle $120^{\circ}$. (in $cm^{2}$)

Is it true that the distance travelled by a circular wheel of diameter $d \text{ cm}$ in one revolution is $2 \pi d \text{ cm}$? Why?

If the radius of a circle is doubled,its area becomes $\ldots \ldots \ldots$ times the area of the original circle.

With the vertices $A, B$ and $C$ of a triangle $ABC$ as centres,arcs are drawn with radii $5 \, cm$ each as shown in the figure. If $AB = 14 \, cm, BC = 48 \, cm$ and $CA = 50 \, cm$,then find the area of the shaded region. (Use $\pi = 3.14$) (in $cm^2$)

In $\odot(O, r)$,chord $\overline{AB}$ subtends a right angle at the centre. The area of the minor segment $\overline{AB} \cup \widehat{ACB}$ is $114 \, cm^2$ and the area of $\Delta OAB$ is $200 \, cm^2$. Then,the area of the minor sector $OACB$ is ......... $cm^2$.

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 $cm^2$.