Assume that x (t) = b cos (w0t) = u (t) is a solution of the van der Pol Equation 4.19. Assume that the damping parameter is small and keep terms in u (t) to first order in μ. Show that b = 2a and u (t) – (μa3/4w0) sin (3w0t) is a solution. Produce a phase diagram of x versus x and produce plots of x (t) and x (t) for values of a = 1, w0 = 1, and μ = 0.5.