Hello, I was wondering if anyone could explain this to me. Although I know the answer, I'm confused as to how it's obtain. I know that it's the magnitude times the sines and cosines then you add the sines and the cosines for the two Fs. What I'm having a hard time understanding is the finding the angles used for sine and cosine. Sometimes my teacher used what appeared to be the reference angle, sometimes the angles themselves. I have no idea of how to obtain the angles. Are the angles of the F1 and F2 related? Thank you in advance.