For a man,the angle of elevation of the highest point of the temple situated east of him is $60^\circ$. On walking $240 \ m$ to the north,the angle of elevation is reduced to $30^\circ$. The height of the temple is:

Two parallel towers $A$ and $B$ of different heights are at some distance $d$ on the same level ground. If the angle of elevation of a point $P$ at $20\,m$ height on tower $B$ from a point $Q$ at $10\,m$ height on tower $A$ is $\theta$,and this angle is equal to half the angle of elevation of point $R$ at $50\,m$ height on tower $A$ from point $P$ on tower $B$,then $\theta$ is equal to....$^o$

The angle of elevation of an object from a point $P$ on the level ground is $\alpha$. Moving $d$ metres on the ground towards the object, the angle of elevation is found to be $\beta$. Then the height (in metres) of the object is

An aeroplane flying horizontally $1 \ km$ above the ground is observed at an elevation of $60^\circ$ and after $10$ seconds the elevation is observed to be $30^\circ$. The uniform speed of the aeroplane in $km/h$ is

The angle of elevation of a cliff at a point $A$ on the ground and a point $B$,$100 \ m$ vertically above $A$,are $\alpha$ and $\beta$ respectively. The height of the cliff is

The sum of the angles of elevation of the top of a tower from two points distant $a$ and $b$ from the base and in the same straight line with it is $90^{\circ}$. Then,the height of the tower is