Chapter 5.6, Problem 4P

In each of Problems $1$ through $13$, find the solutions of the given initial value problem. Draw the graphs of the solution and of the forcing function; explain how they are related.

$y\text{'}\text{'}+4y=\sin t-u_{\pi }(t)\sin (t-\pi );$

$y(0)=0,$ $y\text{'}(0)=0$