Axis of parabola: y=0
Therefore, equation of incident ray: y=2
Point of intersection of parabola and ray: (1,2)
Property: Ray parallel to axis of parabola passes through focus on reflection.
(If the ray is incident from outside the parabola, it passes through the focus upon extension.)
Focus of parabola: (1,0)
Therefore, equation of reflected ray: Equation of line joining (1,2) and (1,0).
Required equation: x=1