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Angle Geometry

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Find the Unknown Angles

  • Determine the unknown angles
    • How do you know?
    • Show detail in your work
  • Compare in your groups

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What we know

  • Sum of angles in a triangle is 180 degrees
  • Straight line rule
    • A straight line is 180 degrees
  • Are these the same?
    • Make a triangle using a ruler
    • Cut and reassemble to a straight line

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What We Know

  • Parallel lines inspire the C theorem, F theorem, and Z theorem

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Find the Unknown Angles

  • On your whiteboard, determine the unknown angles
    • How do you know?
    • Show detail in your work
  • Compare in your groups

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Find the Unknown Angles

  • On your whiteboard, determine the unknown angles
    • How do you know?
    • Show as much detail in your work
  • Compare in your groups

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Triangulation!

  • Draw a pentagon
  • Divide into the smallest number of triangles you can
  • Compare with your group
  • What is the sum of interior angles in the pentagon?

What about an n-gon?

  • What is the smallest number of triangles inside an n-gon?
  • What is the sum of the interior angles inside the n-gon?