For determining the support reactions at A and B of a three hinged arch, points B and Care joined
and produced to intersect the load line at D and a line parallel to the load line through A at D'.
Distances AD, DD' and AD' when measured were 4 cm, 3 cm and 5 cm respectively. The angle
between the reactions at A and B is
(A) 30°
(B) 45°
(C) 60°
(D) 90