A = (3, 5, 2)
B = (9, -1, 5)
u = Vector(A, B)
a = Segment((3, 0, 0), (3, 5, 0))
b = Segment((3, 5, 0), (3, 5, 2))
c = Segment((0, 0, 0), (3, 0, 0))
d = Segment((0, 0, 0), (9, 0, 0))
e = Segment((9, 0, 0), (9, -1, 0))
f = Segment((9, -1, 0), (9, -1, 5))