engineering problem.....statics problem that deals with beam,equilibrium

[Sanky H]

of force etc.? A traffic light is mounted by a cable stretched between two poles which are W = 50 ft.
apart and H = 40 ft. tall. The light is mounted a = 10 ft. to the right of the left pole, and
weighs 100 lb. The cable is composed of stainless steel, and has a diameter of d = 3/8 in.
The poles have a diameter of D = 18 in. and are made of air dried Douglas fir. If the
minimum clearance between the bottom of the traffic light (which is b = 4.5 ft. tall) and
the ground is 35 ft., determine the required pre-tension in the cable.