There are 20 pillars of equal height on a circular ground any two non adjacent pillars joined by a beam. Then the number of such beams are:

Suppose that 20 pillars of the same height have been erected along the boundary of a circular stadium. If the top of each pillar has been connected by beams with the top of all its non-adjacent pillars, then the total number of beams is

Suppose that 20 pillars of the same height have been erected along the boundary of a circular stadium. If the top of each pillar has been connected by beams with the top of all its non-adjacent pillars, then the total number of beams is

Diagonal joins any two adjacent vertices of a polygon .

Two pillars of equal height stand on either side of a roadway which is 120 m wide. At a point in the road between the pillars, the angles of elevation of the pillars are 60^@ and 30^@ . Find the height of each pillars to the nearest metre and position of the point from both the pillars.

Two pillars of equal heights stand on either side of a road which is 100m wide.At a point on the road between the pillars,the angles of elevations of the tops of the pillars are 30^(@) and 45^(@). Find the height of each pillar and position of the point on the road.

Two pillars of equal height stand on either side of a road which is 150m wide. At a point on the road between the pillars the angle of elevation of the top of the pillars are 60° and 30°. Find the height of each pillar and the position of the point on the road.