William is walking straight across a field towards a vertical flagpole .He observes that when he is at point A ,the angle of elevation of T, the top of the flagpole is 30degrees and when he is at point B, on the same side of the flagpole as A, the angle of elevation of T is 45degrees .The distance between A and Bis 20 metres . Using a scale of 1cm to represent 4m ,construct a single diagram to show the relative positions of A, B and T .b. Using a suitable construction on the same diagram, find the height of the flagpole