7-7 6th grade math

1
7-76th grade math

• Triangles

2
Objective

• To classify and draw triangles, and find missing
  angles in triangles.
• Why? To further your knowledge in measurement
  and geometry and keeping building a strong
  foundation in MG in HS

3
California State Standards

• MG 2.3 Draw triangles from information about
  them (e.g., a right isosceles triangle).
• AF 1.1 Write and solve one-step equations
  in one variable.
• AF 3.2 Express in symbolic form simple
  relationships arising from geometry
• MG 2.0 Identify and describe the properties of
  two-dimensional figures.
• MR 2.4 Use a variety of methods, such as words,
  numbers, symbols, charts, graphs, tables,
  diagrams, and models, to explain mathematical
  reasoning.

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Vocabulary

• Triangles
• 3 sided figure and the sum of the angles are
  180. Remember that a triangle is ½ a square or
  rectangle (whose angles measure 360).
• Congruent triangles
• Triangles with the same size and shape

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Vocabulary

• Equilateral triangle
• A triangle with all three sides congruent
• Scalene triangle
• A triangle with no sides congruent (all 3 sides
  are different)
• Isosceles triangle
• A triangle with 2 sides congruent sides
• Right triangle
• A triangle with a right angle (only 1 angle is
  needed)

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Vocabulary

• Acute triangle
• A triangle with all three angles with acute
  measures
• Obtuse triangle
• A triangle with an obtuse angle (only 1 angle is
  needed) ?

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Classifying Triangles

• Classified by Sides
• Three congruent sides
• - equilateral triangle
• Two congruent sides
• - isosceles triangle
• - may be acute, right, or obtuse
• No congruent sides
• - scalene triangle
• -may be acute, right, or obtuse

• Classified by Angles
• All acute angles
• - acute triangle
• - may be equilateral, isosceles, or scalene
• One right angle
• - right triangle
• - may be isosceles or scalene
• One obtuse angle
• - obtuse triangle
• -may be isosceles or scalene

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How to Find Missing Angles of a Triangle

• 1) Add the 2 known angles
• 2) Subtract 180 from Step 1
• 3) Check work

• Triangle with known sides 90 and 30.
• 90 30 120
• 180 120 60
• 3rd side 60

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Try It!

• Classify each triangle in 2 ways
• 1.
• 2.
• 3.
• 4.

1. Scalene, right
2. Isosceles, acute
3. Scalene, obtuse
4. Equilateral, acute

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Try Some More!

• Find the m? of the third angle of teach triangle
• 5) ?s 98, 40, ___
• 6) ?s 29, 84, ___
• 7) ?s 72, 46, ___
• 8) ?s 43, 25, ___

• 5) 180 (98 40)
• 42
• Scalene, obtuse
• 6) 180 (29 84)
• 67
• Scalene, acute
• 7) 180 (72 46)
• 62
• Scalene, acute
• 180 (43 25)
• 112
• Scalene, obtuse

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Objective Review

• To classify and draw triangles, and find missing
  angles in triangles.

• Why? You have furthered your knowledge in
  measurement and geometry and keeping building a
  strong foundation in MG in HS
• You can classify and draw triangles according to
  side and angle measures. By knowing that the sum
  of the angles of a triangle is 180, you can find
  the measure of an unknown angle.

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Independent Practice

• Complete problems 10-23
• Copy original problem first.
• Show all work!

• If time, complete Mixed Review 24-30
• If still more time, work on Accelerated Math.