The existence of the icosahedron amounts to the existence of six equiangular lines in . A regular hexagon is defined as a hexagon that is both equilateral and equiangular. Conversely, every two-graph can be represented as a set of equiangular lines. Another common measure of quality is based on equiangular skew. The only equiangular triangle is the equilateral triangle. In particular, the maximum number of equiangular lines in 7 dimensions is 28. Equiangular lines are equivalent to two-graphs. Given a set of equiangular lines, let "c" be the cosine of the common angle. A maximal set of complex equiangular lines is also known as a SIC or SIC-POVM. Moreover, every integer-sided equiangular "p"-gon has "p"-fold rotational symmetry. An equiangular spiral is sometimes used to visualize such sequences. Isogonal polygons are equiangular polygons which alternate two edge lengths. A "regular star polygon" is a self-intersecting, equilateral equiangular polygon. Such rotations are called isoclinic or equiangular rotations, or Clifford displacements. The skeleton has no special organization, comprising equiangular and equiradiate triactines.