Question

what is galancing angle of reflection

Answer 1

When dealing with a beam that is nearly parallel to a surface, it is sometimes more useful to refer to the angle between the beam and the surface, rather than that between the beam and the surface normal, in other words 90° minus the angle of incidence. This small angle is called a glancing angle or grazing angle.

Answer 2

the angle made by the incident ray and the surface on which it is incident is called the glancing angle.