Question

Distingush betwee plain mirror, concave mirror and, convex mirror

Answer 1

A convex mirror is a spherical mirror where the mirrored surface is on the outside of the spherical curve. And a concave mirror is a spherical mirror where the mirrored surface is on the inside of the spherical curve. Plane mirrors produce virtual, upright images that are the same size as the object.

Answer 2

plane mirror is a mirror with a flat(planar) reflective surface.

A convex mirror, diverging mirror, or fish eye mirror is a curved mirror in which the reflective surface bulges toward the light source. 

Convex mirrors reflect light outwards, therefore they are not used to focus light.