A circular arc subtends angle 150° at the centre of a circle of radius 12cm. Calculate the area of the sector of the arc.

A man stands on a tree 150 cm high and sees a boat at an angle of depression of 74°. Find the distance of the boat from the base of the tree.

Find \(\frac{\mathrm d y}{\mathrm d x}\) if \(y = \cos x\).