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 $\ldots \ cm$.

Is the area of the largest circle that can be drawn inside a rectangle of length $a \, cm$ and breadth $b \, cm$ $(a > b)$ equal to $\pi b^{2} \, cm^{2}$? Why?

If the perimeter of a circle is equal to that of a square,then the ratio of their areas is

The length of the minute hand of a clock is $6 \, cm$. The area of the region swept by it in $10 \, \text{minutes}$ is $\ldots \ldots \ldots \ldots \, cm^2$. $(\pi = 3.14)$

In a circle with radius $21 \, cm$,the length of a minor arc is $33 \, cm$. Find the measure of the angle subtended at the centre by this arc. Also,find the area of the minor sector and the area of the minor segment formed by it.

Circumferences of two circles are equal. Is it necessary that their areas be equal? Why?