1. The problem statement, all variables and given/known data Find the general solution for the differential equation 2. Relevant equations y'' + 16y = tan(4t) 3. The attempt at a solution I get C1cos(4t) + C2sin(4t) = 0 for my homogeneous equation. I did the usual method of undetermined coefficients (I think I took all of the derivatives correctly). However I'm getting something strange for yp. I can't really make sense of the solution. Does this have something to do with the fact that the tangent function has discontinuities? Would this be some kind of resonance?