e_x = (-0.4, -0.4)
u = (-2, -2)
e_y = (1, 0)
v = (5, 0)
e_z = (0, 1)
w = (0, 5)
t = 3.25 (slider from 0 to 6.283185307179586, step 0.01)
P: 3.0 * cos(t) * e_x + 3.0 * sin(t) * e_y
Q: P + 4.0 * e_z
a = Segment(P, Q)