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A transformation of space (invertible map of the plane to itself) that
preserves distances is called an isometry of space. Every
isometry of space is of one of the following types:
- the identity (which leaves every point fixed);
- a translation by a vector v;
- a rotation through an angle around a line L;
- a screw motion through an angle around a line L, with
displacement d;
- a reflection in a line P;
- a glide-reflection in a line P with displacement vector
v.
The identity is a particular case of a translation and
of a rotation; rotations are particular cases of screw motions;
and reflections are particular cases of glide-reflections. However,
as in the plane case,
is more intuitive to consider each case separately.
Next: 10.1 Formulas for Symmetries in Cartesian Coordinates
Up: Part II: Three-Dimensional Geometry
Previous: 9.5 Homogeneous Coordinates in Space
The Geometry Center Home PageSilvio Levy
Wed Oct 4 16:41:25 PDT 1995
This document is excerpted from the 30th Edition of the CRC Standard Mathematical Tables and Formulas (CRC Press). Unauthorized duplication is forbidden.