Question

how can you identify the three types of mirror without touching?

Answer 1

the plane mirror will have same height while convex will have elongated height and concave will have diminished inverted image

Answer 2

hey friend 

we can identify which type of mirror it is by observing the image of object formed by it.

plane mirror: if the image is same size as that of object.
convex mirror: if the image is smaller than object.
concave mirror: if the image is larger than the object.

hope you like my answer :)