Dear friends,

Please suggest any method for the solution of the following equation:

$\displaystyle A(sin(at)+\frac{1}{2}sin(2at))+B(cos(at)+cos(2at)) =Dy(t)+\frac{dy}{dt} $

$\displaystyle y(t_1)=y_s $

$\displaystyle t\in(0,t_1)$

A,B,D,a=const

Thank you in advance.