In a circle with radius $21 \ cm$,the perimeter of a minor sector is $64 \ cm$. Then,the length of the arc of that sector is $\ldots \ cm$.

In the figure,arcs are drawn by taking vertices $A, B$ and $C$ of an equilateral triangle of side $10 \, cm$ as centers to intersect the sides $BC, CA$ and $AB$ at their respective mid-points $D, E$ and $F$. Find the area of the shaded region (Use $\pi = 3.14$) (in $cm^2$).

While calculating the area of a circle,its radius was taken to be $6 \, cm$ instead of $5 \, cm$. The calculated area is $\dots \%$ more than the actual area.

In the figure,arcs have been drawn with radii $14 \, cm$ each and with centres $P$,$Q$,and $R$. Find the area of the shaded region (in $cm^{2}$).

In $\odot(O, 7),$ the length of $\widehat{ABC}$ is $14.$ Then,$\ldots \ldots$ holds good.

The ratio of radii of two circles is $2:3$ and the ratio of the angles at the centre of two minor sectors of those circles is $5:2$. Then,the ratio of the areas of those sectors is: