A uniform rod AB of length 3a and weight W is freely hinged to a xed point at the end A. The end B is below the level of A and is attached to one end of a light elastic string of natural length 4a. The other end of the string is attached to a point 0 on a vertical wall. The horizontal distance between A and the wall is So. The string and the rod make angles 9 and 29 respectively with the horizontal (see diagram). The system is in equilibrium with the rod and the string in the same vertical plane. It is given that sin 9 = g and you may use the fact that cos 26 = % Find the angle that the force acting on the rod at A makes with the horizontal