4.5 Isosceles And Equilateral Triangles

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4.5Isosceles And EquilateralTriangles

• 4 Cards

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Isosceles TrianglesVocabulary
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Isosceles Triangle

• symmetrical

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Isosceles Triangle Theorem

• If two sides of a triangle are congruent, then
  the opposite
• angles are
• congruent

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Converse of theIsosceles Triangle Theorem

• If two angles of a triangle are congruent then
  the opposite sides are congruent

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If the vertex of an isosceles triangle is bisected
Then the bisector is a perpendicular bisector of
the base
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Corollary to the Isosceles Triangle Theorem and
Converse

• If a triangle is equilateral then it is
  equiangular
• If a triangle is equiangular then it is
  equilateral

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Ex 1 Prove the Isosceles Triangle Theorem

• If two sides of a triangle are congruent, then
  the opposite angles are congruent

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Ex 1 Prove the Isosceles Triangle Theorem

1. Given

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Ex 1 Prove the Isosceles Triangle Theorem

1. Given

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Ex 1 Prove the Isosceles Triangle Theorem

• Given
• Definition of a bisector

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Ex 1 Prove the Isosceles Triangle Theorem

• Given
• Definition of a bisector

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Ex 1 Prove the Isosceles Triangle Theorem

• Given
• Definition of a bisector
• Reflexive

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Ex 1 Prove the Isosceles Triangle Theorem

• Given
• Definition of a bisector
• Reflexive

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Ex 1 Prove the Isosceles Triangle Theorem

• Given
• Definition of a bisector
• Reflexive
• SAS

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Ex 1 Prove the Isosceles Triangle Theorem

1. Given
2. Definition of a bisector
3. Reflexive
4. SAS

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Ex 1 Prove the Isosceles Triangle Theorem

1. Given
2. Definition of a bisector
3. Reflexive
4. SAS
5. CPCTC

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Ex 2Find the missing angles
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Ex 2Find the missing angles
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Ex 3 Find the missing angles
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Ex 3 Find the missing angles

• Z 90
• Y 27

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Ex 4 Find the missing angles
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Ex 4 Find the missing angles

• N 27
• M 36