Question: for this problem i just need to know when i...

For this problem, I just need to know when I am solving for the equations of equilibrium, how to know whether it is positive or negative when calculating F_x and F_y and when to know whether to use cos or sin for the angle and force. I understand how to solve the problem but differentiating between cos and sin and when it is positive and negative confuses me. Can someone help me understand.