Question

a ray of light is incident normally on a plane mirror.deduce the path of the reflected ray from the first law of reflection.

Answer 1

Is it fine .i think so because first law is angle of incidence is equal to angle of reflection

Answer 2

As the light is reflecting from the plane mirror, according to the 1st law of reflection it will reflect from the surface of the plane mirror making the same angle with the normal to the mirror that it has made during incident.
I. e angel of incidation = angle of reflection.