An arc of length 15cm subtends an angle of 45° at the centre of a circle. Find in terms of, the radius of the circle.

Find the angle subtended at the centre of a circle of radius 5cm by an arc of length cm.

An arc of length 20π cm subtends an angle of 144° at the centre of a circle. Find the radius of the circle.

Find the angle subtended at the centre of a circle of a circle of radius ‘a’ by an arc of lengthcm.

A sector of a circle of radius 4cm contains an angle of 30°. Find the area of the sector.