eq1: (x * y) - (2 * x) - (4 * y) + 4 = 0
A = Center(eq1)
O: (0, 0)
u = Vector(A, O)
eq1' = Translate(eq1, u)
g, f = Directrix(eq1')
B = Point(g)
C = Intersect(g, xAxis)
D = Point(xAxis)
α = Angle(B, C, D)
Kanooniline = Rotate(eq1', α)