After reading [url=http://www.ams.org/notices/200304/fea-escher.pdf]"Artful Mathematics: The Heritage of M. C. Escher"[/url], [br]I asked myself: can I do [url=http://www.wiskundemeisjes.nl/wp-content/uploads/2006/03/geel.jpg]"this"[/url] in Geogebra?[br]This worksheet works faster after downloading (as usual).[br]