Chapter 5: Triangles and Congruence

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Chapter 5Triangles and Congruence

• 5-1 Classifying Triangles

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Classifying Triangles

• Triangles have two types of classes.
• classed by their angles,
• and classed by their sides.

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Classifying Triangles

• Classed by their angles
• acute triangle
• all three angles are acute
• obtuse triangle
• one angle is an obtuse angle
• right triangle
• one angle is a right angle
• equiangular triangle
• all three angles are congruent (they are 60º
  each)

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Classifying Triangles

• Classified by their sides
• equilateral triangle
• all three sides are congruent
• isosceles triangle
• at least two sides are congruent
• scalene triangle
• all three sides are different lengths

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Classifying Triangles

• Classify each triangle by its angles

acute
right
60
equiangular
60
60
obtuse
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Classifying Triangles

• Classify each triangle by its sides.

scalene
20
20
4
4
equilateral
isosceles
20
7
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Opposite and Included

• A side of a triangle is included between two
  angles.
• An angle of a triangle is included between two
  sides.

B
A
C
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Opposite and Included

• A side of a triangle is opposite an angle.
• An angle of a triangle is opposite a side.

B
A
A
C
C
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Practice

• Name the side opposite angle X.

Y
Z
X
X
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Practice

• Name the side included between angle Z and angle
  X.

Y
Z
Z
X
X
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Practice

• Name the angle included between sides XY and YZ.

Y
Y
Z
X
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Practice

• Name the angle opposite side XY.

Y
Z
Z
X
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Assignment

• Practice Worksheet 25
• Do the odd problems first.
• Get my signature. This is your participation
  grade.
• Homework
• Practice Worksheet 25
• the evens
• Practice Worksheet 26
• all problems