The lid of a roof scuttle weighs 75 lb. It is hinged at corners A and B

Question:

The lid of a roof scuttle weighs 75 lb. It is hinged at corners A and B and maintained in the desired position by a rod CD pivoted at C; a pin at end D of the rod fits into one of several holes drilled in the edge of the lid. For the position shown, determine

(a) The magnitude of the force exerted by rod CD,

(b) The reactions at the hinges. Assume that the hinge at B does not exert any axial thrust.