The Polygon Angle-Sum Theorem

Check Skills You’ll Need Find the measure of each angle of quadrilateral ABCD

Classifying Polygon A polygon is a closed plane figure with at least three sides that are segments. The sides intersect only at their endpoints, and no adjacent sides are collinear.

Name the polygon. Then Identify its vertices, sides, and angles. D H B K G M

A CONVEX polygon has no diagonal with points outside the polygon. A CONCAVE polygon has at least one diagonal with points outside the polygon

SidesName 3triangle 4quadrilateral 5pentagon 6hexagon 7heptagon 8octagon 9nonagon 10decagon 11hendecagon 12dodecagon

Complete the table Number of sides of a Polygon Sum of the angle measure ? 7? 8? 9? 10? 11? 12?

Theorem 3 – 9 Polygon Angle-Sum Theorem The sum of the measures of the angles of an n-gon is (n – 2)180.

Find the measure of the angle Y Y 135

Theorem 3 – 10 The sum of the measures of the exterior angles of a polygon, one at each vertex, 360. For the pentagon, m/_ 1 + m/_ 2 + m /_ 3 + m /_ 4 + m /_ 5 =

The game board whose figure is shown has the shape of a regular hexagon. It is packaged in a rectangular box outlined beneath it. The box uses four right triangles made of foam in its four corners. Find m/_ 1 in each foam triangle

End of discussion