I've been playing around with parabolic mirror calculations in my free time, and right now I'm trying to derive the equation for the line that models the angle of reflection off of a point. I understand how to find the angle of incidence and that the reflection will have the same angle off the tangent line to that point, but I can't figure out how to get the equation for the reflection line. Any help would be great. PS Basically what I'm doing is just finding the focus through geometric methods and seeing the intersection of these reflection lines. Thanks.