f(x) = (0.5/2)*sin((2*pi*x)/15)+1.35
plot(f, (0, 60), ymax = 5, ymin = -5)

t = var('t')
vr(t) = (.25)*sin(2*pi*t/5) + 1.45
vs(t) = (1)*sin(2*pi*t/2) + 1.45
ve(t) = (t/40 - 50/40)*sin(11*pi*t/5 - 86*pi) +1.45
plot(vr, (0, 60), color = 'red') + plot(vs, (60, 90), color = 'green') + plot(ve, (90, 180))