A note on cell phones, tardies, and grades

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A note on cell phones, tardies, and grades
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Informal Geometry

• Goal Use postulates and undefined terms

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The undefined terms

• Point a small dot
• Line extends forever in two directions
• Plane flatness that extends forever

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The Postulates

• Postulate 1 Through any two points there is
  exactly one line
• Postulate 2 Through any three points there is
  exactly one plane

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A few more definitions

• Collinear on the same line
• Coplanar on the same plane
• Ray Extends forever in one direction with one
  endpoint
• Segment part of a line with two endpoints

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Example

• Name three points
• Name a line
• Name a ray
• Name a plane

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Drawing example

• Draw three noncollinear points I, T, and N.
• Draw IT, TN, and IN

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Homework

• 17 (15, 16, 27-33, 36, 38, 40)
• Quiz tomorrow!