These are one version of Penrose tiles, which make a famous quasi-periodic tessellation. Quasiperiodic means that they fill the plane without ever becoming a repeating pattern, but any given chunk of them will repeat an infinite number of times. They were a mathematical curiosity until scientists discovered quasicrystals, which had these patterns in nature.[br][br]Some places to learn about these:[br]My favorite: Dave Austin's two articles, [url]http://www.ams.org/samplings/feature-column/fcarc-penrose[/url] and [url]http://www.ams.org/samplings/feature-column/fcarc-ribbons[/url][br]Also: basics at [url]http://intendo.com/penrose[/url][br]A GeoGebra sketch to look at motions in the tiling [url]http://www.geogebratube.org/material/show/id/10163[/url][br][br]Here's the plain kites and darts with no matching help: [url]http://www.geogebratube.org/material/show/id/35261[/url]