Associative lov:
(u+v)+w = u+(v+w)

A = Intersect(xAxis, yAxis)
B = (1, 3)
C = (5, 4)
D = (9, 2)
u = Vector(A, B)
v = Vector(B, C)
w = Vector(C, D)
uv = Vector(A, C)
vw = Vector(B, D)
uvw = Vector(A, D)