Download Angles of a Triangle

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Lesson 1:
Lesson 2:
Lesson 3:
Lesson 4:
Lesson 5:
Lesson 6:
Lesson 7:
Lesson 8:
4.1/4.2
4.3
4.4/4.5
4.4/4.5
4.7
4.6
4.8
Review
Warm Up
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USING A RULER, draw a triangle that fills the
space in your notes.
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Pass your triangle to a partner.
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Measure the angles in the triangle.
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What do you notice?
Triangle Sum Conjecture
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The sum of the measures of the angles in
every triangle ________________________.
equals 180°
In this lesson we will answer…
 How
are the measures of the angles in a
triangle related?
Using the Triangle Sum Conjecture
Using the Triangle Sum Conjecture
Using the Triangle Sum Conjecture
Angles of a Triangle
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Use the Triangle Sum Conjecture and your
algebra skills to solve for x.
Angles of a Triangle
Angles of a Triangle
Angles of a Triangle
Angles of a Triangle
In this lesson we will answer…
 Do
I remember the parts of an isosceles
triangle?
 Is there anything special about the angles of
an isosceles triangle?
 What can I assume to be true of any
isosceles triangle?
Parts of the Isosceles Triangle
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Using the triangle provided:
Measure AB and BC.
 What is true of these sides?
Fold triangle ABC to compare A and
 What is true of
A and C?
Check with your partners!
C.
Parts of the Isosceles Triangle
DEF: An isosceles
triangle has at least 2
congruent sides
Vertex Angle
Leg
Leg
Base Angle
Base Angle
Base
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Isosceles Triangle Conjecture
If a triangle is isosceles, then
the base angles are congruent
_______________________________.
Converse of the Isosceles Triangle
Conjecture
base angles
If a triangle has congruent
____________________
isosceles
then it is __________________________.
Examples
Examples
Examples
What STUCK with You?
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Complete the Ticket Out the Door.
Explain how you arrived at each answer.
Almost Finished…
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Clear Your Calculator and Turn It Off
 2nd  +  7  1  2 then 2nd  On
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Take out your agenda – copy down due dates
 Quizzes
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Tests
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Homework
 Practice 4.1 and 4.2
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Do NOT pack up until you are told to do so!