Do Now

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Do Now

1. Draw a right triangle. Label the hypotenuse and
   legs.
2. Label the side lengths of this triangle with the
   following lengths 20, 37.5, and 42.5.
3. Do these side lengths create a right triangle?
   Show your work.

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10.1 Triangles Day 2

• Objective Solve problems involving triangles
• Homework
• 10.1 Practice Worksheet- Classifying Triangles

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A triangle can be classified by its sides and by
its angles.

• Classifying by sides
• Equilateral All 3 sides are congruent
• Isosceles 2 sides are congruent
• Scalene No sides are congruent

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Examples
5

• Classification by angles
• Acute All 3 angles less than 90 degrees
• Obtuse One angle is greater than 90 degrees
• Right One angle is exactly 90 degrees
• Equiangular All 3 angles are congruent

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Examples
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Practice Classify the triangle by its sides and
angles.
2.)
1.)
3.)
4.)
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Practice Classify the triangle by its sides and
angles.
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Do-Now
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10.1 Triangles Day 3

• Objective identify angle measures of triangles
• Homework
• 10.1 Practice Worksheet- Finding Angle Measures
  of Triangles

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Finding Angle Measures

• Interior angles of a triangle add up to equal
  180?.

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Examples
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Acute angles of a right triangle are
complementary.
A
B
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Examples
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Examples with Algebra
1) 2)
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Try These

• 1.)

3.)
x
x
40
2x
3x
105
2.)
x
45
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Do Now
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10.1 Triangles Day 4

• Objective use perimeter to find missing side
  lengths of triangles
• Homework
• 10.1 Practice A Worksheet- Using Perimeter to
  Find Missing Side Lengths of Triangles

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Using Perimeter to Find Side Lengths
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Find the unknown side length of the triangle
given the perimeter P. Then classify the triangle
by its side lengths.
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1. The ratio of the angle measures of a triangle
is 3 4 5. Find the angle measures. Then
classify the triangle by its angle measures.
Examples
2. The ratio of the angle measures of a triangle
is 7 12 17. Find the angle measures. Then
classify the triangle by its angle measures.