t = 0.82 (slider from 0 to 1, step 0.02)
a = CurveCartesian(t * 10 * cos(4 * π * t), t * 10 * sin(4 * π * t), t, 0, 1)
A: (t * 10 * cos(4 * π * t), t * 10 * sin(4 * π * t))