Imaginary axis

Real axis

O = (0, 0)
c = Circle(O, 1)
B = Point(c)
C = Point(c)
u = Vector(O, B)
v = Vector(O, C)
a: x(u) x(v) - y(u) y(v)
b: x(u) y(v) + y(u) x(v)
D: (a, b)
w = Vector(O, D)