Only three regular polygons can tessellate in a plane.

define tessellation.
name the three regular polygons
explain why a regular polygon cannot form a tessellation.
explain why only these three can form tessellations

Repeaterd use of figures of one kind or more to cover a plane without gaps and without overlaps is called tessellation.
only equilateral triangles squares and regular hexagons can form tessellation.
it is because each of their interior angles should be a factor of 360°. only these 3 kinds satisfy this.