1. Triangle Congruence Unit 1: Day 8

2. Perimeter of the preimage • Scale Factor = Perimeter of the Image
Warm-Up #
Write one net rule for a reflection across the y-axis followed by a rotation 90 degrees about the origin.
The perimeter of the image is 80 units. This image was created from the pre-image with a magnitude of 5. What is the perimeter of the pre-image?
Hint: Remember the formula:
Perimeter of the preimage • Scale Factor = Perimeter of the Image

3. HW Check

4. What does it mean for two figures to be congruent?
Essential Question #8
What does it mean for two figures to be congruent?

5. What characteristics did Translations, Rotations, and Reflections share?
When the preimage and image have the same size and shape, we call the transformation an isometry, or a rigid motion.
Definition: Two plane figures (polygons) are congruent if and only if one can be obtained from the other by a sequence of rigid motions.

6. Congruent Segments have the same length.
Congruent Angles have the same measure (or degrees)

7. Triangle Congruence
Two triangles are congruent if and only if one can be obtained from the other by rigid motions

8. Properties of Congruence

13. CPCTC …
CPCTC is:
Corresponding parts of a triangle are the sides and angles that are images of each other
Corresponding Parts of Congruent Triangles are Congruent (abbreviated as CPCTC) – If two triangles are congruent, then the corresponding sides and corresponding angles are congruent.

14. List all corresponding sides:

15. List all corresponding angles:

16. Complete the three Examples at the bottom of the page.
HW is the right side of the page.

17. Standard CW: Complete #1-7
Honors CW: Complete #1-8
The CW is due at the end of class for a grade!