Question

Why angle of incidence always equal to angle of reflection?

Answer 1

Light always travels in straight line and follows Fermat principle which states that Light selects a path which takes the least time to travel.
Hence during reflection of light , always angle of incidence= angle of reflection.

Answer 2

becoz it is given by the law and if u experiment we would be able to hear the reflected sound only at the angle equal to angle of incidence.this us my answer .