What best describes a semi regular tessellation?

Answer 1

A semi-regular tessellation is using multiple copies of two (or more) regular polygons so as to cover a plane without gaps or overlaps. The different shapes have sides of the same length and the shapes meet at vertices in the same (or exact reverse) order.

The image used with this question:

http://file2.answcdn.com/answ-cld/image/upload/w_300,h_115,c_fill,g_face:center,q_60,f_jpg/v1401482497/u6cbkstcqpiibq3485hr.png

uses a regular quadrilateral (a square) and an equilateral triangle. At each vertex, these two shapes, starting with the shape at the top, meet in the following order: TSTTS ot STTST.

Answer 2

A tessellation that uses more than one type of regular polygon

Answer 3

It is a tessellation using two or more regular polygons such that the same set of polygons in the same order surround each polygon of a given shape.