yes
Yes it can
No, not normally
true!! apex.
false
No. See, for example, the top image in the attached link.
Yes.
Yes, it can.
yes
Yes. A regular tessellation can be created from either an equilateral triangle, a square, or a hexagon.
M.C. Escher (dutch)
Yes it can
Venus Equilateral - collection - was created in 1947.
No, not normally
Sporting Triangles was created in 1987.
Pittsburgh Triangles was created in 1974.
Dayton Triangles was created in 1913.
A tessellation is created when a shape is repeated over and over again covering a plane without any gaps or overlaps.