OK, I am having some issues with some trusses. The first one is a platt truss, h = 8 m, length of horizontal beams = 8 m F = 340 kN occurs at each of the 5 pts between the supports, one is a pin, the other is a roller. I get the force in a diagonal to be ~240 kN, but the answer in the book is 96.2 kN, a factor of 2.5. I did a bunch of searches on google, and I think my procedure is right, even according to the examples. So where does that 2.5 come from? Or is the book wrong? Part of me thinks that the book is wrong, but this isn't the first problem in this chapter that would be true. Thanks!!!