The symmetry operation , etc., which is equivalent to , where the bar denotes an improper rotation.
Mirror Plane
See also
Mirror Image, Mirror Pair, Mirror SymmetryExplore with Wolfram|Alpha
Cite this as:
Weisstein, Eric W. "Mirror Plane." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/MirrorPlane.html