The area of a circle is $346.5 \, cm^2$. Find its radius (in $cm$).

In a circle with radius $10 \, cm$,the area of a minor sector is $75 \, cm^2$. Then,the length of the arc of that sector is $\ldots \, cm$.

In covering a distance $s$ metres,a circular wheel of radius $r$ metres makes $\frac{s}{2 \pi r}$ revolutions. Is this statement true? Why?

The radius of a wheel of a car is $21 \, cm$. If it makes $800$ rotations per minute,find the speed of the car in $km/h$.

The area of $\odot(O, r)$ is $240 \, cm^2$. In $\odot(O, r)$,minor arc $\widehat{ACB}$ subtends an angle of measure $45^\circ$ at the centre. Then,the area of minor sector $OACB$ is $\dots \dots \dots \, cm^2$.

Find the area of the shaded field shown in the figure.