Geometric transformation that preserves the measures of the figures (lengths, angles) or distances.
The word isometry also refers to the property of that which is isometric. We can determine the isometry of two figures by examining the measures of their sides and their corresponding angles.
- A direct isometry preserves the orientation of the plane.
Translations and rotations are direct isometries.
- An opposite isometry is an isometry that inverts the orientation of the plane.
An opposite isometry is also called a flip.
Orthogonal symmetries, also called reflections, and glide reflection symmetries are opposite isometries.