1. The problem statement, all variables and given/known data Express 8.5sin(290t+325) as C1cos(wt)+C2sin(wt) 2. Relevant equations The previous parts of the problem actually ask to find the wave equation itself and write it in different forms. So the above wave equation can also be expressed as 8.5cos(290t-125) or as -8.5cos(290t+55) etc. 3. The attempt at a solution Can I use the following trig identity: A cos (wt) + B sin (wt) = (A^2 + B^2)^1/2 cos (wt + tan^-1 (-B/A)) ?