The following diagram shows an incident ray AO and the normal ON on a plane mirror. Find the angle of incidence and angle of reflection.
ON is perpendicular on a plane mirror Angle of Incidence $$\angle i (\angle AON)$$i.e. Angle between incident ray and normal ray = $$90^0 - 30^0 = 60^0$$ Angle of Reflection = $$60^0$$ $$\therefore \ \ \angle i = \angle r$$ $$\therefore$$ Angle between Incident and reflected ray I.e. $$\angle AOB$$ = $$60 + 60 = 120^0$$