The sum of all interior angles of a regular polygon is twice the sum of all its exterior angles. The number of sides of the polygon is

$A$ circular road runs around a circular garden. If the difference between the circumference of the outer circle and the inner circle is $44\, m$,then find the width of the road in $m$.

$A$ circular park has a path of uniform width around it. The difference between the outer and inner circumferences of the circular path is $132 \, m$. Its width is.....$m$.

The cost of levelling a rectangular ground at $Rs. 1.25$ per $sq. metre$ is $Rs. 900$. If the length of the ground is $30$ $metres$,then the width is? (in $metres$)

The area of a trapezium is $2500 \, m^2$. One of its parallel sides is $75 \, m$. If the distance between the two parallel sides is $40 \, m$,then find the length of the other parallel side in $m$.

In the given figure,$OP = PQ = 14 \, cm$ and semicircles are drawn on $OP$,$PQ$,and $OQ$ as diameters. Then,the perimeter of the shaded area is . . . . . . $cm$.