9.5 Symmetry Then: You drew reflections and rotations of figures. Now: 1. Identify line and rotational symmetries in two-dimensional figures. 2. Identify plane and axis symmetry in three-dimensional figures.

9.5 Symmetry I. Symmetry- a figure has symmetry if there exists a rigid motion, such as a reflection, translation, rotation, or glide reflection, that maps the figure onto itself. w51HUu1bdNE/Uj8c74efTYI/AAAAAAAALpM/MW6GVjkrN68/s1600/Excellent+examples+of+symmetry+in+nature+(11+photos ).jpg

9.5 Symmetry II. Types of Symmetry A. Line symmetry- also called reflection symmetry. Occurs when a figure in a plane can be mapped onto itself by a reflection in a line, called a line of symmetry (or axis of symmetry).

9.5 Symmetry B. Identify Line Symmetry State whether each figure has line symmetry. Write yes or not. If so, draw all line of symmetry and state their number

9.5 Symmetry C. Rotational symmetry- also called radial symmetry Occurs when a figure in a plane can be mapped onto itself by a rotation between 0  and 360  about the center of the figure, called the center of symmetry (or point of symmetry).

9.5 Symmetry 1. Order of symmetry- the number of times a figure maps onto itself as it rotates from 0  and 360 . 2. Magnitude of symmetry- also called angle of symmetry, the smallest angle through which a figure can be rotated so that it maps onto itself. 3. Order and magnitude are related by the following: Magnitude = 360   Order

9.5 Symmetry 4. Identify Rotational Symmetry State whether the figure has rotational symmetry. Write yes or no. If so, locate the center of symmetry, and state the order and magnitude of symmetry. a. b.c.

9.5 Symmetry III. Symmetry in Three Dimensional Figures A. Plane symmetry- when a three-dimensional figure can be mapped onto itself by a reflection in a plane. B. Axis symmetry- when a three-dimensional figure can be mapped onto itself by a rotation between 0  and 360  in a line.

9.5 Symmetry C. Identify Three-Dimensional Symmetry State whether the figure has plane symmetry, axis symmetry, both or neither

9.5 Symmetry Assignment:Page #9-34 all, 42-44, 46,