Day 8 - Proofs using CPCTC.notebook

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Get your assignment sheets out and fill it outGrab a worksheet packet from the back tableGet out a couple of sheets of paper and a pencil

Topic: Proofs using CPCTCEssential Question: What must you show in a proof before you can use CPCTC.

14 1/7-1/8

Congruent

Triangle proof

practice # 1-7, 9,

12-14, 16

classwork

15 1/7-1/8

Pg. 271-272 #

4,7-9, 11,17-22

all

Homework

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Classwork :Congruent Triangles Proof practice

# 1-7, 9, 12-14, 16 All

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Answers

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Notes: CPCTC

What does CPCTC stand for?

CPCTC

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In other words, if two trianlges are congruent,then their corresponding parts (angles andsides) are congruent.

Suppose ∆RST≅∆LMO.

What angles and sides are congruent because of CPCTC.

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CPCTC will be used as a reason in a proof to say 2 sides or angles are congruent in a triangle after you have already proven the triangle are congruent using one of the congruence postulates.

Ex.

A

B

CD

Given: AB ≅ BC; <ABD ≅ < CBD

Prove: AD ≅ CD

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Sometime, CPCTC is used as a step to prove something else in a given diagram, such as midpoints, perpendicular lines, or parallel lines.

Given: BM ≅MN; EM ≅ MZ

Prove: BE II ZN

# 20 Change the "Given" and "Prove" statement to the one given.

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Guided Practice:

Complete proofs # 21 and 22

Change the "Prove" statement in # 22 to read "AC bisects <BAD

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Prove: AC bisects <BAD

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Using CPCTC with algebra to find angle sizes or side lengths

A B

CD

AB = 5x - 12BC = 3x + 2CD = 8x - 42

Find X, then find the lengths of AB, BC, and CD. Is ABCD a rhombus (4 equal sides)

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Classwork/Homework

From book or on worksheet, Pg. 271-272 # 4, 7-9, 11,17-22 all

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