Static 2d body, force in member unknown

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togo
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Homework Statement


Truss diagram rotated sideways, with joints labelled A through G and supports at F and G. A 200 kN load points left at joint D and a 100 kN load points down at joint C, with dimensions of 5 m, 2.5 m, 8 m and 2 m marked.


Find stress or force in member AE

Homework Equations


torque = force x distance


The Attempt at a Solution


Solution out of book is 142 kN

Attempts:
Mb = -(200kN)(2.5m) + (.895AE)(5) + 510
= 111 Kn

Mc = -(3m)(170kN) + (.895AE)(5)
= 114 kN

Md = (-80)(2.5) - (100kN)(7.5m) + (.895AE)(2.5)
= 424.60 kN

Solving for force at F and G, Fy = 80 kN and Gy = 130 kN

where did I go wrong?
 

Discussion

There are still reaction forces at F and G that you havn't took into consideration.
 
For B and C the forces at G and F are directly in line therefore they cancel out. In my calculation for D, I did take F into account