A parabola mirror is kept along y^2=4xand two light rays parallel to its axis are reflected along one straightline. If one of the incident light rays is at 3 units distance from the axis,then find the distance of the other incident ray from the axis. Question from Class 12 Chapter ParabolaApne doubts clear karein ab Whatsapp par bhi. Try it now. We have parabola `y^(2)=4x`. <br> Let two incident rays AP and BQ, which are parallel to axis of the parabola, strikes the parabola at points A and B, respectively. <br> After reflection, both the pass through the focus S(1,0). <br> <img src="https://d10lpgp6xz60nq.cloudfront.net/physics_images/CEN_MATH_CG_3e_C05_S01_080_S01.png" width="80%"> <br> Therefore, AB is focal chord. <br> Let point A be `(t^(2),2t)`. <br> Distance of ray AP is 3 units from axis. <br> `:." "2t=3` <br> `or" "t=(3)/(2)` <br> Coordinates of point B are `((1)/(t^(2)),(-2)/(t))` (other end of focal chord). <br> Distance of B from the axis `=(2)/(t)=(4)/(3)`