Math 20-2

Chapter 2 Properties of Angles and Triangles

Lesson 2.6 Proving Congruent Triangles

GOAL

The goal of this lesson is stated at the top of page 107 in your textbook, and is also written below.
Keep this in mind as you work through the lesson material.

Use deductive reasoning to prove that triangles are congruent.

Print

Sorry, not a complete playlist of facts,  but a start.
This is a list of conditions for triangle congruence.
You can print this an use it like a formula sheet (but check with your teacher about use on tests and quizzes, etc.

LINK
https://drive.google.com/file/d/1sfZFABPbRPCf0xfvIgtoBV-dgJA6ij-M/view?usp=sharing

Explore...

Try to answer the question in the sidebar on page 107.

Demonstration

Below is an interactive version of the Sierpinski triangle.

Watch

Video Tutorial

Learn About the Math

Information and Examples that present the ideas of this lesson

TEXT Page 107

Read/Work through the Learn About the Math section on Page 107 in your textbook.

Example 1  Using reasoning in a two-column proof

TEXT Pages 107 - 108

Work through Example 1 on Pages 107 - 108 in your textbook.

Watch

Video Tutorial

Apply the Math  (Examples)

Examples will give you TOOLS for solving problems, and also show you that there may be different ways to approach a question.

YOUR TURN gives YOU the chance to try to do a problem ON YOUR OWN,  using the examples as models.

Example 2  Reasoning about congruency to prove that sides are equal

TEXT Page 109

Work through Example 2 on Page 109  in your textbook.

Watch

Video Tutorial

Your Turn

Use the Video Tutorial for help, or to check your work, BUT... you should do your best to do this question ON YOUR OWN FIRST!

Video Tutorial

Example 3  Reasoning about congruency to prove that angles are equal

TEXT Pages 109 - 110

Work through Example 3 on Pages 109 - 110 in your textbook.

Watch

Video Tutorial

Your Turn

Use the Video Tutorial for help, or to check your work, BUT... you should do your best to do this question ON YOUR OWN FIRST!

Video Tutorial

Example 4  Reasoning about congruency to prove an angle relationship

Note,  I didn’t do this example.
Why?
If two sides in a triangle are equal, then the two angles opposite those sides are equal.
So the triangle is isosceles.
The text is asking for a proof of something that (I believe) we can assume is true.

TEXT Pages 110 - 111

Work through Example 4 on Pages 110 - 111 in your textbook.

Watch

Video Tutorial

Your Turn

Use the Video Tutorial for help, or to check your work, BUT... you should do your best to do this question ON YOUR OWN FIRST!

Video Tutorial

In Summary

Key Ideas and Need to Know 
Presents and summarizes  the main new concepts of the lesson

•	Carefully read through each of the bullet points in this section.

•	If you are unclear about any of these ideas,  ASK YOUR TEACHER FOR HELP!

Practice Problems

Doing Practice Problems

Practice problems reinforce the math presented in this lesson.

•	Work through the practice problems for this lesson.
	These problems are for practice, you don’t need to hand them in!
	(your teacher may assign specific questions for you to complete)

•	Use the answers in the back of the book to CHECK YOUR WORK!

•	If you make a mistake, TRY TO FIX IT!

•	If you need help or want more information, view the video solutions provided.

•	If you still need more help,  CONTACT YOUR TEACHER!

Types of Practice Problems

Check Your Understanding questions require basic understanding of the ideas of the  lesson.

Practising questions will require you to dig deeper for a solution.

Closing  A summary question that often asks YOU to explain ideas in your own words.

Extending questions offer enrichment and extension.

Notes

Question 16,    I didn’t do a video for this one.

Question 18,    I didn’t do a video for this one.

Question 10,    the demonstration of the important theorem
LINK

Question 20,    a rhombus demonstration
LINK

Video Solution Links

Check your work for every problem you do!
If you make a mistake,  try to fix it!
Use the video solutions for more information.
If a problem still doesn’t make sense, ASK YOUR TEACHER FOR HELP!

({{"Question 1", "Question 2", "Question 3", "Question 4", "Question 5"}, {"Question 6", "Question 7", "Question 8", "Question 9", "Question 10"}, {"Question 11", "Question 12", "Question 13", "Question 14", "Question 15"}, { , "Question 17",  , "Question 19", "Question 20"}})