SEMI-REGULAR TESSELLATIONS are composed of 2 or more different regular polygons.
Just like regular tessellations, every vertex looks the same and the sum of the interior angles at each vertex is 360°. Even more precisely, each vertex has the same pattern of polygons around it.
There are only 8 combinations of 2 or more regular polygons that create semi-regular tessellations.
1. Each vertex looks the same - four triangles and one hexagon:
2. Each vertex looks the same - one triangle and two dodecagons:
3. Each vertex looks the same - one square, one hexagon and one dodecagon: 90 + 120 + 150 = 360.
4. Each vertex looks the same - three triangles and two squares: