Find the shaded area in the given circle with radius $20 cm, \angle AOB= 90°$. [Take $\mathrm{\pi } = 3.14$]

$OAB$ is a quadrant of a circle of radius $14 cm$. A semicircle is drawn on diameter $OB$. Calculate the shaded area.

$OAB$ is a quadrant of a circle of radius $14 cm$. A semicircle is drawn on diameter $OB$. Calculate the length of arc $AB$.

$PQ$ is the diameter of the semicircle with centre $O. OR$ is the diameter of the small circle inscribed in it. Find the shaded area if $PQ=21 cm$. 

The quadrants shown in the figure given below are each of radius $7 \mathrm{cm}$. Calculate the area of the shaded portion.

Two small circles touching each other externally and of radius $6 cm$ are inscribed in a circle. Find the shaded area.

[Take $\mathrm{\pi }=\frac{22}{7}$]

Two semicircles and one circle of same radius $5 cm$ are inscribed in a rectangle. Find the area of shaded region. [Take $\mathrm{\pi }=\frac{22}{7}$]