Interior Angles of a Polygon

The sum of angles of a polygon—what do triangles have to do with it? Given the formula for the sum of the measures of the interior angles of a convex polygon, pupils explain why it finds the sum. Learners may use a diagram to help with their explanations.

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CCSS: Designed
Additional Tags
Instructional Ideas
  • Provide several opportunities for class members to draw diagonals from one vertex of different polygons to determine the number of triangles formed
Classroom Considerations
  • The class should be familiar with the formula to find the sum of the interior angles of a polygon
  • Individuals should understand the difference between concave and convex polygons
Pros
  • Contains descriptions of misconceptions at different levels of understanding
  • Includes examples of pupils' work
Cons
  • None
Common Core