1. The problem statement, all variables and given/known data Solve: PDE: 9Uxx=Utt BC: U(0, t) = U(∏, t) = 0 IC: U(x, 0) = sin4x + 7sin5x Ut = x 0 < x < ∏/2 = ∏ - x ∏/2 < x < ∏ 2. Relevant equations Fourier Sine Series and Cosine Series Equations 3. The attempt at a solution (see attached photo) I am getting very lost at the tail end of this problem (the bottom right hand portion of the attached photo). I can't seem to really figure out how to apply the Fourier Sine Series equations with the given PDE. Any help would be truly appreciated!