$A$ round table cover has six equal designs as shown in the figure. If the radius of the cover is $28\, cm$,find the cost of making the designs at the rate of $Rs.\, 0.35$ per $cm^2$. (in $Rs.$) (Use $\sqrt{3}=1.7$)

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 $\pi=\frac{22}{7}$]

Tick the correct answer in the following and justify your choice: If the perimeter and the area of a circle are numerically equal,then the radius of the circle is ......... $units$.

In $Fig.$,$ABCD$ is a square of side $14 \, cm$. With centres $A, B, C$ and $D$,four circles are drawn such that each circle touches externally two of the remaining three circles. Find the area of the shaded region (in $cm^2$). $\left[\text{Use } \pi = \frac{22}{7}\right]$

In the figure,a square $OABC$ is inscribed in a quadrant $OPBQ$. If $OA = 20 \, cm,$ find the area of the shaded region. (in $cm^2$) (Use $\pi = 3.14$)

In the given figure,$OACB$ is a quadrant of a circle with centre $O$ and radius $3.5 \, cm$. If $OD = 2 \, cm$,find the area of the:
$(i)$ quadrant $OACB$,
$(ii)$ shaded region. $\left[ \text{Use } \pi = \frac{22}{7} \right]$