Fbc(cos?) - Fab((4/(sqrt(65)) = 0
Fab((7/(sqrt65)) - Fbc(sin?) - 50 = 0
Fcd(cosf) - Fbc(cos?) = 0
Fbc(sin?) + Fcd(sinf) – 100 =0

you have unknowns of f ? Fbc Fab Fcd
5 unknowns in 4 equations cannot be solved.

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