I have to solve the equation in range from 0 to 7pi:
with boundary conditions
This is what I can do, but then I have a problem.
How to draw it with
Evaluate in phase space? I also have to substitute the solution to the left side of differential equation and draw this formula in range of 0 < t < 7pi, on the y axis from -2 to 2. I have to use ParametricPlot and Evaluate, but don't know how. I mean, I tried to do so but it didn't work :/