Question

when a light ray strike with 45degree angle of reflection

Answer 1

Answer:

The angle of incidence is measured from the normal to the mirror at the point where the ray strikes the mirror. Here the angle of incidence = 90–45 = 45 deg. So the reflected ray is at 45 deg, both from the normal to the mirror as well as the plane of the mirror.

To clarify it further: If the angle between the mirror and the incident ray is 15 deg, the angle of incidence = 90–15 = 75 deg. Here the angle of reflection is 75 deg measured from the normal to the mirror..