1 Symmetry in two dimensions
In Section 1 we discuss intuitive ideas of symmetry for a two-dimensional figure, and define the set of symmetries of such a figure. We then view these symmetries as functions that combine under composition, and show that the resulting structure has properties known as closure, identity, inverses and associativity. We use these properties to define a group in Section 3.
Click the link below to open Section 1 (15 pages, 623KB).