AB and CD are respectively arcs of two concentric circles of radii 21 cm. and 7 cm. with centre O (See figure). If ∠AOB = 30°, find the area of the shaded region.

(use π = 22/7)

Find the area of the shaded region in figure, where ABCD is a square of side 10 cm. and semicircles are drawn with each side of the square as diameter

(use π = 3.14)

Find the area of the shaded region in figure, if ABCD is a square of side 7 cm. and APD and BPC are semicircles.

(use π = 22/7)

In 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 shaded region.

(use π = 22/7)

Calculate the area of the designed region in figure, common between the two quadrants of the circles of radius 10 cm. each.

(use π = 3.14)