Prove that a vertical line and a line going from a point on a parabola to the focus of the parabola form equal angles with the tangent line of the point on the parabola.
Focus = 1/4a (maybe relevant)
The Attempt at a Solution
I know how to prove that the triangle from the vertical line, midpoint of Focus point to an arbitrary line and the point on the parabola is equal to a triangle that goes from focus point to point on parabola to midpoint.
However, I have no clue how to show that these two angles are the same. I can find the slope of each line, obviously, but where to go from here?