(a) Verify that a particular solution, G_{R}\left(t-t^{\prime}\right)=-\frac{1}{\omega} \theta\left(t-t^{\prime}\right) \sin \omega\left(t-t^{\prime}\right) which is referred to as the retarded Green's function, satisfies the Green function differential equation and the continuity conditions.Hint: Use

problem 2 and limsin r/r = 0