t = 0 (slider from 0 to 20, step 0.1)
a = CurveCartesian((2 * (u - sin(u))), (2 * (1 - cos(u))), u, 0, t)
O: ((2 * t), 2)
c = Circle(O, 2)
M: ((2 * (t - sin(t))), (2 * (1 - cos(t))))