I have uploaded the question with solution at this address: http://i41.tinypic.com/o5xm5j.jpg All I need to know is why in the moment equation "NA*a - F*b = 0" the forces Nb and Nc aren't included. Is it because the moment is being calculated about the dot in the middle, and the other two forces are pointing at it? If the Nc force wasn't pointing directly at that center point (and was pointing slightly above), would I have to calculate the net moment including the horizontal and vertical components of Nc from point C? When do I know not to include a force in the moment calculation? Thanks!