4.4 - CPCTC

Do Now:

Write the converse of the Polygon Congruence Postulate and give an example. Do you think the converse is true?

4.4 - CPCTC

Agenda

Objective and Preview

Quick Review

CPCTC

Flowchart Proof

Practice

Objective and Preview

OBJ: Use congruence of triangles to conclude congruence of corresponding parts.

Preview:

CPCTC: Corresponding Parts of Congruent Triangles are Congruent

Flowchart proofs organize thoughts visually

Quick Review

1.) Make a congruence statement:

BADC _________

2.) State the 5 valid tests of triangle congruence

CPCTC

3.) If you have proven ABCDEF, what six things can you say? (Think back to the Do Now)

4.) This idea is often stated as Corresponding Parts of Congruent Triangles are Congruent

5.) It is abbreviated as CPCTC

*CPCTC can be used as a justification in proofs*

6.) Example

Prove that opposite angles in a parallelogram are congruent.

How can you prove this using what you know about triangles?

Flowchart Proof

A way to visually organize information

Statements are written in boxes

Justifications are written underneath

Arrows connect boxes that are logically related

Arrow points from one box to a box that follows logically from it

Example

pg. 236 in your book

7.) Example

Finish the flowchart proof:

8.) Example

Write a flowchart proof:

Given:

Prove:

Start by interpreting the diagram and analyzing the information.

Before you leave

Summarize your notes

HW: Section 4.4 Part 1 p. 240-241 #18, 20-22, 27-29