1. The problem statement, all variables and given/known data Find the amplitude and phase shift of the following two superposed harmonic oscillations. 2. Relevant equations x1(t)=3sin(2∏t+∏/4) x2(t)=3cos(2∏t) 3. The attempt at a solution Ok normally i would be able to do this, however one oscillation is cos and the other sin, so i can't use the trig identity for sin+sin or cos+cos. Is it possible to turn 3sin(2∏t+∏/4) into 3cos(2∏t+∏/4+∏/2) or is that invalid?