1. 9-1 Reflections
Rigor – Students will correctly reflect images over a given line of reflection and understand the definition of a reflection
Relevance – Reflections describe rigid motion

2. Introduction into Transformations
Workbook pages 37 – 40 Vocabulary:
Transformation
Pre-image
Image
Coordinate notation
Prime notation
Rigid motion / isometry
Translation
Rotation
Reflection

3. Reflection defined
A reflection is a rigid transformation such that the line of reflection is a perpendicular bisector for the segments connecting each pre-image point to its corresponding image.

4. Reflections Using Graph Paper
Reflect ∆𝐴𝐵𝐶 over 3 different lines: across the x-axis, y-axis, and the line y = x.
Compare the coordinates of the images to the pre-image What pattern do you notice? A C B
Pre-image
x-axis
y-axis
y = x
A(-5, 6)
B( -5, 2)
C( 1, 2)

5. Reflections Using Tracing Paper
Turn in your workbook to pg 369 example 1 and follow the instructions in the bullets to reflect the triangle and quadrilateral. Use scratch paper or tracing paper.
Draw a segment connecting corresponding vertices of the pre-image and image.
What do you notice?

6. Notation for Reflections
𝑟 𝑙𝑖𝑛𝑒 𝑜𝑓 𝑟𝑒𝑓𝑙𝑒𝑐𝑡𝑖𝑜𝑛 (𝑝𝑟𝑒−𝑖𝑚𝑎𝑔𝑒)
“Reflect triangle ABC across the line y = 4” would be written as 𝑟 𝑦=4 (∆𝐴𝐵𝐶)
Special Function Rules
Highlight the special reflection rules for the coordinate plane on workbook pg371

7. Workbook Examples Pg 371 example 3 pg 372 #1, 2, 4 (use tracing paper)
pg 373 #9 – 11 (using special function rules)
Reflections worksheet: Resource Page
For the last problem, reflect y = x2 + 3 over the line y = x.
THIS WORKSHEET WILL BE A CLASSWORK GRADE

8. Reflection Methods Recap
On graph paper - count squares
Tracing Paper – Use when not using graph paper
Special Function Rules - Used for reflections across the x-axis, y-axis, and y=x

9. 9-1 Assignments Primary Assignment: Secondary Assignment:
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Codes:
Period 1: (Due Monday 7am)
Period 3: (Due Monday 7am)
Period 7: (Due Monday 7am)
Secondary Assignment:
Workbook pg 375 #5, 6, 8 – 11; pg 376 #1, 3, 5 – 7

10. 9-1 Honors Assignments Primary Assignment: Secondary Assignment:
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Codes:
Period 2: (Due Tuesday 7am)
Period 4: (Due Tuesday 7am)
Period 6: (Due Tuesday 7am)
Secondary Assignment:
Workbook pg 375 #5, 6, 8 – 11; pg 376 #1, 3 – 7