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

If the angles of a quadrilateral are (3y + 10)°, (2y + 30)°, (y + 20)° and 4y°. Find the value of y.

A square tile has side 30 cm. How many of these tiles will cover a rectangular floor of length 7.2m and width 4.2m?

Find the length of a chord which subtends an angle of 90° at the centre of a circle whose radius is 8 cm.

A chord of a circle subtends an angle of 120° at the centre of a circle of diameter \(4\sqrt{3} cm\). Calculate the area of the major sector.