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.
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°