The aircraft-hangar door opens and closes slowly by means of a motor, which draws in the c...

The aircraft-hangar door opens and closes slowly by means of a motor, which draws in the cable AB. If the door is made in two sections (bifold) and each section has a uniform weight of 300 lb and height L = 10 ft, determine the force on the cable when θ = 90°. The sections are pin connected at C and D and the bottom is attached to a roller that travels along the vertical track.