Question

Why incident ray passed through center of curvature reflected back through its owm path?

Answer 1

A ray of light passing through the centre of curvature of a concave mirrorretraces its path (gets reflected along the same path), because as the ray of light passes through centre of curvature of a concave mirror it strikes the mirror along the normal i.e. it incidences on to the mirror at 90 degree.

Answer 2

It is a rule of physics that an incident ray that passes through the centre of curvature of a concave or a convex mirror is reflected back obliquely without any deviation