If the angles of elevation of the top of a tower from two points at distances 'a' and 'b' (where a > b) from the foot of the tower and in the same straight line with it are complementary, then the height of the tower is:

Two persons are on diametrically opposite sides of a tower. They measure the angles of elevation of the top of the tower as 30° and 60° respectively. If the height of the tower is 100 m, what is the approximate distance between the two persons?

At a point on level ground, the tangent of the angle of elevation of the top of a tower is found to be 56. On walking 70 m towards the tower, the tangent of the angle of elevation of the top of the tower is found to be 98. What is the height of the tower?