Rotations in the Plane
This page delves into the concept of rotations in geometry. A rotation is described as a turn of a figure around a fixed point.
The key elements defining a rotation are:
- The center point of rotation
- The angle of rotation
- The direction (clockwise or counterclockwise)
Highlight: Like translations, rotations also preserve lengths, alignments, angles, and areas of the original figure.
An example is provided showing a figure and its rotated image around a center point O.
Example: The diagram illustrates a shape (Figure 1) and its rotated version (Figure 4) around a center point, demonstrating a 180° clockwise rotation.
Note: If the angle and direction are not specified, a rotation is assumed to be 180°.
The page also introduces the concept of frises et pavages (friezes and tessellations), which are patterns created using these transformations.
Vocabulary: Rotation - A geometric transformation that turns a figure around a fixed point by a certain angle.