# 6-1 The Polygon Angle-Sum Theorems

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6-1 The Polygon Angle-Sum Theorems

Polygon Angle-Sum Theorem
The sum of the measures of the interior angles of a n-gon is 𝑛−2 180

NUMBER OF SIDES NAME 3 Triangle 4 Quadrilateral 5 Pentagon 6 Hexagon 7 Heptagon 8 Octagon 9 Nonagon 10 Decagon

Problem 1: Finding a Polygon Angle Sum
What is the sum of the interior angle measures of a heptagon?

What is the sum of the interior angle measures of a 17-gon?

The sum of the interior angle measures of a polygon is 1980
The sum of the interior angle measures of a polygon is How can you find the number of sides in the polygon?

Corollary to the Polygon Angle-Sum Theorem
The measure of each interior angle of a regular n-gon is 𝑛−2 180 𝑛

Problem 2: Using the Polygon Angle-Sum Theorem
The common housefly has eyes that consist of approximately 4000 facets. Each facet is a regular hexagon. What is the measure of each interior angle in on hexagonal facet?

What is the measure of each interior angle in a regular nonagon?

Problem 3: Using the Polygon Angle-Sum Theorem

You can draw exterior angles at any vertex of a polygon
You can draw exterior angles at any vertex of a polygon. The figures below show that the sum of the measures of the exterior angles, one at each vertex is 360.

Polygon Exterior Angle-Sum Theorem
The sum of the measures of the exterior angles of a polygon, one at each vertex, is 360. For the pentagon

Problem 4: Finding an Exterior Angle Measure

What is the measure of an exterior angle of a regular nonagon?