I can find the magnitude of Fnet from free body diagrams or from addition of vectors. My issue however is how do I know when to subtract the angle I found with the corner angle? I've attached two questions and the answers to them.
In the first question, the angle that was found is the resultant angle for Fnet. In the second question, the angle that is found is then subtracted by the corner angle. How do I know what angle is the correct one for Fnet? Can someone please explain to me possibly with a diagram?