The length of the minute hand of a clock is $12\,cm$. The area of the region swept by it in $5$ minutes is $\ldots \ldots \ldots \,cm^2$. $(\pi=3.14)$

An umbrella has $8$ ribs which are equally spaced (see $Fig.$). Assuming the umbrella to be a flat circle of radius $45 \, cm ,$ find the area between the two consecutive ribs of the umbrella. [use $\pi=\frac{22}{7}$]

Find the area of the shaded design in the figure where $ABCD$ is a square of side $10 \, cm$ and semicircles are drawn with each side of the square as diameter. (in $cm^2$) (Use $\pi = 3.14$)

The area of a sector formed by a $12\,cm$ long arc in a circle with radius $12\,cm$ is $\ldots \ldots \ldots \, cm^{2}$.

The radii of two circles are $8 \, cm$ and $6 \, cm$ respectively. Find the radius of the circle having area equal to the sum of the areas of the two circles. [use $\pi = \frac{22}{7}$] (in $cm$)

As shown in the diagram,the radii of two concentric circles are $21 \, cm$ and $28 \, cm$. If $m \angle AOB = 40^\circ$,find the area of the shaded region. (in $cm^2$)