Question

two mirrors m and n are perpendicular to each other at O .Ray AB is incident to the mirror m at point B and reflected back in the direction BC which is again incident o the mirror n at point C Ray CD is the finally reflected ray.Prove that ray AB is parallel to Ray CD

Answer 1

So we have theta asthe angle of incidence on the first mirror m.  Let Fie be the angle of incidence on the second mirror  n.

see the enclosed document.

df7fab10c6e595609f77c3f8f5719b75.docx

Answer 2

You should remember incident ray = reflected ray. if you see alternate angles are equal then the lines will be parallel. or if corresponding angles are equal then lines are parallel as well