On a horizontal plane there is a vertical tower with a flag pole on the top of the tower. At a point 9 metres away from the foot of the tower the angle of elevation of the top and bottom of the flag pole are 60° and 30° respectively. Find the height of the tower and flag pole mounted on it. OR From a building 60 metres high the angles of depression of the top and bottom of a lamp-post are 30° and 60° respectively. Find the distance between the lamp-post and building. Also find the difference of height between building and lamp-post.