411 REFERENCE · Wiktionary
Penrose triangle
Reference material by Wiktionary contributors. This retains its source identity and is not 411 news reporting.
English
thumb|Penrose triangle
Etymology
en English mathematician Roger Penrose = 1931 who popularised it in the 1950s.
Noun
An optical illusion depicting an impossible solid object made of three straight beams of square cross section which meet pairwise at right angles at the vertices of the triangle they form.
See also
en Necker cube
en eponyms
en Optical illusions