Warm%20Up

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Warm Up
Lesson Presentation
Lesson Quiz
Holt McDougal Geometry
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• Warm Up
• 1. If ?ABC ? ?DEF, then ?A ? ? and BC ? ?
  .
• 2. What is the distance between (3, 4) and (1,
  5)?
• 3. If ?1 ? ?2, why is ab?
• 4. List methods used to prove two triangles
  congruent.

?D
Alternate Interior Angles
SSS, SAS, ASA, AAS, HL
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Objective
Use CPCTC to prove parts of triangles are
congruent.
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Vocabulary
CPCTC
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CPCTC is an abbreviation for the phrase
Corresponding Parts of Congruent Triangles are
Congruent. It can be used as a justification in
a proof after you have proven two triangles
congruent.
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Example 1 Engineering Application
A and B are on the edges of a ravine. What is AB?

One angle pair is congruent, because they are
vertical angles. Two pairs of sides are
congruent, because their lengths are equal.
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Check It Out! Example 1
A landscape architect sets up the triangles shown
in the figure to find the distance JK across a
pond. What is JK?
One angle pair is congruent, because they are
vertical angles.
Two pairs of sides are congruent, because their
lengths are equal. Therefore the two triangles
are congruent by SAS. By CPCTC, the third side
pair is congruent, so JK 41 ft.
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Classwork/Homework

• 4.7 CPCTC W/S