Reflections Reflections Reflections Reflections Reflections Chapter 9.1

Recognize and draw lines of symmetry and points of symmetry. Draw reflected images. reflection Recognize and draw lines of symmetry and points of symmetry. line of reflection isometry line of symmetry point of symmetry Standard 22.0 Students know the effect of rigid motions on figures in the coordinate plane and space, including rotations, translations, and reflections. (Key) Lesson 1 MI/Vocab

Isometries Maps Preimage onto an Image Point P  Point P’ (“P prime”) Preserves Length AB = A’B’ Angle measures mA = mA’ Parallel Lines l // m  l’ // m’ Betweenness If X is between A and B then X’ is between A’ and B’

Isometries Reflection – “flip” Orientation is switched R REFLECTION

Isometries Q Q Translation Translation Translation Translation – “slide” Is not turned Q Q Translation Translation Translation

Isometries G G G Rotation Rotation Rotation Rotation G Rotation – “turn” Pivoted around a point G G G Rotation Rotation Rotation Rotation G

Reflections Line of reflection – Mirror line A reflection over a line m is a transformation that maps every point P to a point P’, so that the following properties are true: If P is not on m, then m is the perpendicular bisector of PP’ If P is on m, then P = P’

Symmetry A figure has a line of symmetry if the figure can be mapped onto itself by a reflection over the line.

Draw the reflected image of quadrilateral ABCD in line n. Lesson 1 CYP1

Lesson 1 CS1

Determine how many lines of symmetry a regular pentagon has. Draw Lines of Symmetry Determine how many lines of symmetry a regular pentagon has. A regular pentagon has five lines of symmetry. Answer: 5 Lesson 1 Ex4

A. Determine how many lines of symmetry an equilateral triangle has. B. 2 C. 3 D. 6 A B C D Lesson 1 CYP4

Homework Chapter 9-1 Pg 501 1 – 4, 6, 8, 9 10 – 17, 21 – 23, 25 – 28 Don’t worry about “Point of Symmetry”