I have the following ODE:
$$y'' - 2y'\tan(x)-y=\sin(x)$$
I am at a loss where to start. All the methods described in my textbook assume knowledge of the complementary function to solve $2$nd order ODEs with variable coefficients. However in a case like this, it seems that the roots of the related homogeneous ODE, $$y'' - 2y'\tan(x)-y=0 ,$$ cannot be found.
Could anyone give me a hint on how to start tackling this problem? Or what methods to use?