In $\odot (P, 20)$,the area of a minor sector is $150\, cm^2$. The length of the arc corresponding to that sector is $\dots\, cm$.

In a circle with radius $6.3\, cm$,a minor arc subtends an angle of measure $40^{\circ}$ at the centre. The area of the minor sector corresponding to that arc is $\ldots \ldots cm^{2}$.

In a circle with radius $7 \, cm$,the perimeter of a minor sector is $\frac{86}{3} \, cm$. Then,the area of that minor sector is $\ldots \ldots \ldots \ldots cm^2$.

Nine circular designs are made in a square show-piece as shown in the diagram. If the radius of each circle is $21\, cm$,find the area of the region without design. (in $cm^2$)

The area of the circle that can be inscribed in a square of side $6 \, cm$ is (in $cm^2$) (in $\pi$)

As shown in the diagram,$\overline{OA}$ and $\overline{OB}$ are two radii of $\odot(O, 35 \text{ cm})$ perpendicular to each other. If $OD = 12 \text{ cm}$,find the area of the shaded region. (in $\text{cm}^2$)