Question : The angle of elevation of the top of a tower from a point on the ground is 30° and moving 70 m towards the tower it becomes 60°. The height of the tower is:

Question : From a tower 125 metres high, the angle of depression of two objects, which are in a horizontal line through the base of the tower, are $45^{\circ}$ and $30^{\circ}$ and they are on the same side of the tower. The distance (in metres) between the objects is:

Question : TF is a tower with point F on the ground. The angle of elevation of T from A is $\tan\;x^{\circ}=\frac{2}{5}$ and AF = 200 m. The angle of elevation of T from a nearer point B is $y^{\circ}$ with BF = 80 m. The value of $y$ is:

Question : A pilot in an aeroplane at an altitude of 200 metres observes two points lying on either side of a river. If the angles of depression of the two points be $45^{\circ}$ and $60^{\circ}$, then the width of the river is:

Question : In $\Delta ABC$, the external bisector of the angles, $\angle B$ and $\angle C$ meet at the point $O$. If $\angle A = 70^\circ$, then the measure of $\angle BOC$: