why is it impossible to tesselate a plane with the following regular polygons located at one vertex: 1 regular hexagon, 1 regular pentagon,1 square

Question

1 regular hexagon, 1 regular pentagon,1 squarewhy is it impossible to tesselate a plane with the following regular polygons located at one vertex:

Answer 1

Only equilateral triangles, squares, and regular hexagons can tessellate, i.e., cover a surface without gaps and without any other polygon.

 

What do you mean by "located at one vertex?"