Penrose triangle

The Penrose triangle, also known as the Penrose tribar, the impossible tribar,^[1] or the impossible triangle,^[2] is a triangular impossible object, an optical illusion consisting of an object which can be depicted in a perspective drawing, but cannot exist as a solid object. It was first created by the Swedish artist Oscar Reutersvärd in 1934.^[3] Independently from Reutersvärd, the triangle was devised and popularized in the 1950s by psychiatrist Lionel Penrose and his son, prominent Nobel Prize-winning mathematician Sir Roger Penrose, who described it as "impossibility in its purest form".^[4] It is featured prominently in the works of artist M. C. Escher, whose earlier depictions of impossible objects partly inspired it.