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Day 8 - Proofs using CPCTC.notebook
January 08, 2013
Get your assignment sheets out and fill it out
Grab a worksheet packet from the back table
Get out a couple of sheets of paper and a pencil
Topic: Proofs using CPCTC
Essential Question: What must you show in a proof before you can
use CPCTC.
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1/7-1/8
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1/7-1/8
Congruent
Triangle proof
classwork
practice # 1-7, 9,
12-14, 16
Pg. 271-272 #
4,7-9, 11,17-22 Homework
all
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Day 8 - Proofs using CPCTC.notebook
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Day 8 - Proofs using CPCTC.notebook
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Classwork :
Congruent Triangles Proof practice
# 1-7, 9, 12-14, 16 All
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Day 8 - Proofs using CPCTC.notebook
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Answers
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Day 8 - Proofs using CPCTC.notebook
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Notes: CPCTC
What does CPCTC stand for?
C
P
C
T
C
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Day 8 - Proofs using CPCTC.notebook
January 08, 2013
In other words, if two trianlges are congruent,
then their corresponding parts (angles and
sides) are congruent.
Suppose ∆RST≅∆LMO.
What angles and sides are congruent because
of CPCTC.
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Day 8 - Proofs using CPCTC.notebook
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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.
B
Ex.
Given: AB ≅ BC; <ABD ≅ < CBD
Prove: AD ≅ CD
A
C
D
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Day 8 - Proofs using CPCTC.notebook
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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.
# 20 Change the "Given" and "Prove" statement to the one given.
Given: BM ≅MN; EM ≅ MZ
Prove: BE II ZN
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Day 8 - Proofs using CPCTC.notebook
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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
D
B
C
AB = 5x - 12
BC = 3x + 2
CD = 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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