1. 9-2 Reflections

2. Key Concepts: R stands for reflection and the Subscript tells you what to reflect on (ex: R x-axis) The “line of reflection” is what you reflect on Reflection: keeps size and shape, it’s always a RIGID MOTION or ISOMETRY!!

3. Just watch! Don’t need to write. R k = reflect over line k R l = reflect over line l k l

4. Example R x-axis R y-axis R y = x R y =-x (3,-4) (-3,4) (4,3) (-4, -3) Original: (3,4)

5. TOO Graph each original Find and graph the reflection across: – x-axis – y-axis – y = x – y = -x 1) (-2,-3)2) (4,1) Answers: 1) (-2,3) (2,-3) (-3,-2) (3, 2) 2) (4,-1) (-4,1) (1,4) (-1, -4)

6. Rules Look at the answers that you got for the example and the 2 TOO. Write mappings for reflecting across: – x-axis (x stays the same!) – y-axis (y stays the same!) – y = x (they flip flop, signs STAY) – y = -x (flip flop, signs CHANGE) But what about other lines????? (x,y) → (x,-y) (x,y) → (-x,y) (x,y) → (y,x) (x,y) → (-y, -x)

7. Point P has coordinates (3,4). What are the coordinates of:

8. Reflections of Triangles

9. Homework Pg. 557 # 7-14, 28-29, 37 (2 graphs, # 13 & 14) OR: Print from my website!