1. The problem statement, all variables and given/known data In an LC-circuit, with: L = 64 mH C = 121 nF where at t=0, Q = 10*10^-6 C , (the charge on the capasitor) I = 0,3 A, (the current through the inductor) Write an expression for the charge on the capacitor and the current through the inductor as a function of time. 3. The attempt at a solution I've tried this several times from stratch now, and while I do get an answer, according to the book I'm wrong. The standard form of a solution for Q, is Q = Qm*cos(wt + phi), where phi is the phase displacement. My strategy is to write both the expressions for Q and I, both containing the unknown parameters phi and Qm, and solving the system of two equations with two unknowns. However, I always get phi = -1,20, whereas the answer in the book is phi = -0,922. I've attached my latest handwritten attempt at a solution, thanks for any help!