The Sum of Angles in a Triangle

This The Sum of Angles in a Triangle handout & reference also includes:

An informative lesson contains a brief explanation of how the sum of the angles of a triangle is a line. The lesson continues with determining the missing angle in a triangle, or solving for a variable. Using the sum of the angles, the lesson introduces how to find the measure of an exterior angle of a triangle. 

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CCSS: Designed
Instructional Ideas

  • Review solving linear equations
  • Have the class determine why the sum of the angles of a triangle equal 180 degrees
Classroom Considerations

  • Make sure the class knows how to solve the types of equations needed 
  • The lesson is eighth in an 11-part unit on congruence and similarity
Pros

  • Includes a video lecture from a teacher
  • Provides several problems of different levels
Cons

  • The lesson relies on direct instruction as the sole instructional strategy
Common Core