The truss supports a sign board as shown in the figure. Calculate the reactions at A and the force in the member FG produced by the horizontal wind load of 60lb per vertical foot of a sign.
The Attempt at a Solution
Everything is right except for Ax which should equal 257lb in the left direction. Now my problem is when I set up my equations, they always fix my directions (negative answer means wrong assumption). However in this case, I had to use trigonometry to solve for Gx and FG. When I plugged in the numbers, I get the wrong direction. How do I find the proper direction of the forces when using trigonometry?