Three vertical poles of heights and at the vertices and of a subtend angles respectively at the circumcentre of the triangle. If and are in AP, then are in
is a point on the segment joining the feet of two vertical poles of height and The angles of elevation of the top of the poles from are 45 each. Then, the square of the distance between the top of the poles is
The angle of elevation of the top of a tower at a point on the ground is . If on walking 20 m toward the tower the angle of elevation becomes , then the height of the tower is