A man on the top of a vertical observation tower observes a car moving at a uniform speed coming directly towards it. If it takes 12 minutes for the angle of depression to changed from `30^@` to `45^@` , how soon after this will the car reach the observation tower? Give your answer correct to the nearest second.

A straight highway leads to the foot of tower. Ramaiah standing at the top of the tower observes a car at an angle of depression 30^(@) . The car is approaching the foot of the tower with a uniform speed. Six seconds later, the angle of depression of the car is found to be 60^(@) . Find the time taken by the car to reach the foot of the tower from this point.

An observer on the top of a tree ,finds the angle of depression of a car moving towards the tree to be 30^@ .After 3 minutes this angle becomes 60 ^@ .After how much more time , the car will reach the tree ?

From the point on the top of a palace of 60 metres height, it is observed that the angle of depression of the tip and the foot of a tower are 30^@ and 60^@ respectively. Find the height of the tower.

A man standing on a railway bridge 5sqrt3 meters high, observes the engine of a train at an angle of depression 30^@ . But after 2 seconds, he observes the engine at an angle of depression 45^@ on the other side of the bridge. Find the speed of the train.

A man standing on a railway overbirdge of 5sqrt3 m height observed the engine of the train from one side of the bridge at an angle of depression of 30^@ . But just after 2 seconds, he observed the engine at an angle of depression of 45^@ from the other side of the bridge. Find the speed of the train.

Laxmidevi standing on a railway overbridge of 5sqrt(3) metres height observed the engine of the train from one side of the bridge of depression of 30^(@) . But just after 2 seconds, she observed the engine at an angle of depression of 45^(@) from the other side of the bridge. Find the speed of the train in metres per second.

To a person standing at the middle point of the horizontal straight line joining the feet of two vertical posts of the same height, the angle of elevation of the top of each post appears to be 30^@ . After walking 40metres towards one of them , the person observes that the angle of elevation of the top of the same post has changed to 60^@ . Find the distance between the two posts.