Download Geometry Fall 2012 Lesson 22 (CPCTC)

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Lesson Plan #23
Class: Geometry
Date: Wednesday November 9th, 2016
Topic: Proving corresponding parts of congruent triangles congruent.
Aim: How can we prove corresponding parts of congruent triangles congruent?
HW #23:
Objectives:
1) Students will be able to prove deductively that corresponding parts of congruent triangles congruent.
Do Now:
Answer the following questions:
1) The centroid of a triangle is the intersection of the
2)
3)
4)
5)
6)
7)
8) Which one of the following statements
is true?
A) The circumcenter lies in the interior of
a right triangle.
B) The orthocenter lies in the interior of
an obtuse triangle.
C) The centroid lies on the hypotenuse of
a right triangle.
D) The circumcenter lies in the exterior of
an of an obtuse triangle.
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PROCEDURE:
Write the Aim and Do Now
Get students working!
Take attendance
Give Back HW
Collect HW
Go over the Do Now
What does it mean that two triangles are congruent? It could mean that all six pairs of corresponding parts are congruent.
How could we prove that certain pairs of parts in triangles are congruent? Hmm…first prove that the triangles are congruent!
Example: Complete the missing reasons in the proof below
Statements
Reasons
ABC , BD bisects  ABC
2.  3  4
( a.  a.)
2.
3. BD  BD
( s.  s.)
3.
1. In
4.
1. Given
BD  AC
4. Given
5.  1 and  2 are right angles
6.  1  2
7. ABD  CBD
8.
AD  CD
Sample Test Questions:
1)
2)
5. Definition of perpendicular lines (4)
( a.  a.)
6. If two angles are right angles, then they are congruent. (5)
7.
8. Corresponding parts of congruent triangles are congruent. (7)
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Medial Summary: Why does proving triangles congruent allow us to conclude that their corresponding
parts are congruent?
Group Work (Engagement): How can you use the definition of congruent triangles to prove the statements
below?
3)
4)
5)
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Final Summary: Writing in math!
How could you go about proving that one part in a triangle is congruent to a part of another triangle?
If Enough Time: