Same-side exterior angle converse theorem states that if two lines are intersected by a transversal and the same-side exterior angle are congruent, then the two lines are parallel. One can apply this theorem to the given case, and thus lines A and B are parallel.
X= means that it is the vertical line on that number, so x=1 would be the vertical lines going through 1, which would be in the middle of the parabola, thus having symmetry
