AB and CD are respectively arcs of two concentric circles of radii 21 cm and 7 cm and centre O. If ZAOB = `30^@`, find the area of the shaded region.

Two concentric circles have radii 20 cm and 15 cm. Find the area of ring shaped region

In fig., a square OABC is inscribed in a quadrant OPBQ. If OA = 20 cm, find the area of the shaded region.

Two concentric circles are of radii 5 cm and 3 cm. Find the length of the chord of the larger circle which touches the smaller circle.

In figure, OACB is a quadrant of a circle 3.5 cm. OD = 2 cm, find the area of shaded region.

With the same centre O ,draw two circles of radii 4 cm and 2.5 cm.

Two concentric circular loops of radii 1 cm and 20 cm are placed coaxially. Find mutual inductance of the arrangement.

In fig., ABC is a quadrant of a circle of radius 14 cm and a semi circle is drawn with BC as diameter. Find the area of the shaded region.

A square of side 3 cm is inscribed in a circle. Find the area of the shaded portion.

In Fig. 12.27, AB and CD are two diameters of a circle (with centre O) perpendicular to each other and OD is the diameter of the smaller circle. If OA = 7 cm, find the area of the shaded region.