Question

A man on the top of a vertical tower observes a car moving at a uniform speed coming directly towards it. If it takes 12 minutes for the angle of depression to change its measure from 30 to 45, how soon after this, will the car reach the tower ?

Answer 1

Let time taken is t'

height of the top is h meter

and distance between point O to B is x meter

We know, the angles 30 and 45 degree respectively.

for further clarification see the attachement.