The equation for the parabola is

x^2-2xy+y^2-2sqrt(2)x-2sqrt(2)y=0

I know I have to use cot2θ= (A-C)/B

But then I get cot2θ= (1-1)/-2 = 0

I know what to do if I got an actual value, but I'm stuck since it's 0.

I would really appreciate any help. :)