In biologyline symmetryis calledbilateralsymmetry. The planerepresentationof a leaf, for example,may
havebilateralsymmetry—itcan be split downthe middleinto two halvesthat are reflectionsof eachother.
(Source:http://commons.wikimedia.org/wiki/Image:Leaf_Diagram_1.png,License:GNUFree Documentation
License)
RotationalSymmetry
A plane(two-dimensional)figurehasrotationalsymmetryif the figurecan be rotatedand the imageof
everypointof the figureis a pointon the originalfigure.
In effect, this says that the rotatedimageis the originalfigureitself.
Anotherway to expressthis is to say: After beingrotated,the figurelooksexactlyas it did beforethe rotation.
Notethat the centerof rotationis the “center”of the figure.