A signboard 4.5m by 6.0m in the area is supported by two frames, as shown in the figure below. All members are actually 50 mm by 100 mm in cross-section. Calculate the stress in each member due to a horizontal wind load of 960 N/m² on the sign. Assume all joints are connected by pins and that one-quarter of the total wind force acts at B and at C. Neglect the possibility of buckling of the compression members. Neglect the weight of the structure