u 

v

A = (1, 1)
B = (4, 3)
u = Vector(A, B)
C = (8, 2)
v = Vector(A, C)
A2: x(u)
A3: y(u)
B2: x(v)
B3: y(v)
A5: A2 * B3 - A3 * B2