
 Symmetry Encyclopedia Article, Definition, History, Biography (Site not responding. Last check: 20071022) 
  The triangles with this symmetry are isosceles, the quadrilaterals with this symmetry are the geometric kites and the isosceles trapezoids. 
  Group cm can also be described as a rectangular checkerboard pattern, where the pattern of each of the two tiles is symmetric in, say, the horizontal direction, or looking at it differently (by shifting half a tile) a checkerboard pattern where the two tiles are each other's mirror image. 
  Group cmm can be described as a checkerboard pattern of 2fold rotational tiles and their mirror image, or looking at it differently (by shifting half a tile in both directions) a checkerboard pattern of two horizontally and vertically symmetric tiles. 
 encyclopedia.localcolorart.com /encyclopedia/Symmetry (4068 words) 
