Topic: Angles E2.3 – Interior Angles of Polygons

Ontario Curriculum Expectation:

6.E2.3 use the properties of supplementary angles, complementary angles, opposite angles, and interior and exterior angles to solve for unknown angle measures.

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Any polygon can be made up of a different number of triangles.

And the pattern continues…

The above only works for polygons that are convex.

Finding the Unknown Angle

Shape: Pentagon (5 sides)

Sum of interior angles: 540º

Interior angles: 132º, 90º, 74º, 129º, ?º

132° + 90° + 74° + 129° + ?º = 540°

? = 540° − 132° − 90° − 74° − 129°

? = 115°