B 459 450 Fc F F Fc F sin45° sin(90°+0) sin(45°-θ) F=28.3KN,F4=22.4KNF C FD C F’ C BF FA F D A C B F 45 O 45 O F’ C FA  sin 45 sin( 90 ) sin( 45 ) '  − = + = o o C o FA F F FC 28.3KN,FA 22.4KN ' = =