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# SAS-sy Triangles

Lesson 4 of 10

## Objective: Students will be able to identify when and how to prove triangles congruent using SAS congruence theorem.

#### Do Now and Vocabulary

*15 min*

This Do Now reviews identifying corresponding parts of congruent figures and focuses on using algebra.

The first page of student notes introduces the idea of an included side using student-created drawings. To help students differentiate angles and sides I highly recommend having students use highlighters, makers or colored pencils for the student notes in this lesson. The reflections in this lesson also discuss how to use shading techniques.

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#### Triangle Proof Project

*5 min*

In today's lesson, you may want to give students time to pick their partners and develop a schedule for when and where they will be completing their video. The documents for this project can be found, here. This project can be completed throughout the unit or done in it's entirety after completing all the unit lessons.

#### Resources

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A practice proof using SAS is provided for teachers to guide students through. One way to go over this proof with students is to complete the flow-proof with them, and then ask them to complete the 2 column proof (or vice-versa!)

Students can work on the practice proofs in class or for homework. Students will use MP #3 to complete this assignment.

The exit ticket asks students to identify which corresponding angle or segment will allow for a proof of SAS. This reinforces a key vocabulary word, included side. If time remains in class, this is definitely an important topic to review with students. An extension would be to ask students which sides would provide us with SSA, and what does this imply?

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- UNIT 1: Introduction to Geometry: Points, Lines, Planes, and Angles
- UNIT 2: Line-sanity!
- UNIT 3: Transformers and Transformations
- UNIT 4: Tremendous Triangles
- UNIT 5: Three Triangle Topics
- UNIT 6: Pretty Polygons
- UNIT 7: MidTerm Materials
- UNIT 8: Circles
- UNIT 9: 3-D Shapes and Volume
- UNIT 10: Sweet Similar Shapes
- UNIT 11: Trig Trickery
- UNIT 12: Finally Finals

- LESSON 1: Time for Triangles
- LESSON 2: Time for More Triangles
- LESSON 3: SSS for Real
- LESSON 4: SAS-sy Triangles
- LESSON 5: AAS and ASA Fun
- LESSON 6: HL and More Practice with Proofs
- LESSON 7: Isosceles Triangles Forever
- LESSON 8: On the Plane - Coordinate Geometry Proofs
- LESSON 9: Overlapping Triangles
- LESSON 10: Tremendous Triangles Projects