9 6 Identify Symmetry Line Symmetry and Rotational

9. 6 Identify Symmetry Line Symmetry and Rotational Symmetry

LINE SYMMETRY l symmetry A figure in the plane has Line ________ if the figure can be mapped onto itself by a reflection in a line of symmetry l This line of reflection is called a _____. l A figure can have more than one line of symmetry.

Identify lines of symmetry Example 1: 2 ______ How many lines of symmetry do the figures have? 5 ______ 1 _____

On Your Own 1: How many lines of symmetry do the figures have? _________

ROTATIONAL SYMMETRY l l rotational symmetry A figure in a plane has ___________ if the figure can be mapped onto itself by a rotation of 180° or less about the center __________ of the figure. center of rotation This point is called the ___________. To determine rotational symmetry, just……

Rotational Symmetry For example, look at this square: This has rotational symmetry, because a rotation of either 90° or 180° maps the figure onto itself. A 45° rotation does not.

Example 2: Does the figure have rotational symmetry? If so, describe any rotations that map the figure onto itself. a. Regular hexagon b. Kite

On Your Own 2: Do any of the figures have rotation symmetry? If so, describe any rotations that map the figure onto itself. a. b.

Example 3: Identify the line of symmetry and rotational symmetry of the figures below.

EXAMPLE III