Triangle :)
A regular triangle, quadrilateral (i.e., square) and hexagon may be used.
square
which regular polygon can be used to form a tesselation?
Yes it can
No, it is not possible.
A regular polygon will tessellate if its interior angle divides 360 evenly.
The only regular polygons are those with 3, 4 or 6 sides.
Semi-regular tessellation is a tessellation of the plane by 2 or more different convex regular polygons. A semi-regular tessellation combines two or more regular polygons. Each semi-regular tessellation has a tupelo, which designates what kind of regular polygon is used.
It can be used only if the measure of its interior angle is a factor of 360 degrees.
A regular pentagon is one example.
It is extremely difficult to explain how since it is, in fact, impossible!