a necker cube is an example of a(n)
Necker cube The Necker cube is an optical illusion first published as a rhomboid in 1832 by Swiss crystallographer Louis Albert Necker.[1] It is a simple wire-frame drawing of a cube with no visual cues as to its orientation, so it can be interpreted to have either the lower-left or the upper-right square as its front side. Necker cube is used in studies of human visual perception.
Hexagon These symmetries express 9 distinct symmetries of a regular hexagon. John Conway labels these by a letter and group order.[2] r12 is full symmetry, and a1 is no symmetry. d6, a isogonal hexagon constructed by four mirrors can alternate long and short edges, and p6, an isotoxal hexagon constructed with equal edge lengths, but vertices alternating two different internal angles. These two forms are duals of each other and have half the symmetry order of the regular hexagon. The i4 forms are regular hexagons flattened or stretched along one symmetry direction. It can be seen as an elongated rhombus, while d2 and p2 can be seen as horizontally and vertically elongated kites. g2 hexagons, with opposite sides parallel are also called hexagonal parallelogons.