1. Reflections Reflections Reflections Reflections Reflections
Chapter 9.1

2. 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 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

3. 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’

4. Isometries
Reflection – “flip”
Orientation is switched R
REFLECTION

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

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

7. 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’

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

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

10. Lesson 1 CS1

11. 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

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

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