In $\odot(O, 4)$,$\widehat{ACB}$ is a minor arc and $m \angle AOB = 45^\circ$. Then,the length of minor $\widehat{ACB}$ is $\ldots \ldots \ldots \ldots$

If the circumference of a circle and the perimeter of a square are equal,then

The closed figure formed by an arc of a circle and the radii through its end points is called .........

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 $\dots \dots \dots \, cm^2$.

The diagram below is formed by three semicircles. If $OA = OB = 70\, cm,$ find the area of the figure formed (in $cm^2$).

The radius of a circular ground is $56 \, m$. Inside it, a road of width $7 \, m$ runs all along its boundary. Find the area of this road in $m^2$.