Lesson 10-6 Pages 527-531

Polygons

What you will learn!1. How to classify polygons.

2. Determine the sum of the measures of the interior and exterior angles of a polygon.

PolygonPolygonDiagonalDiagonalInterior angleInterior angleRegular polygonRegular polygon

What you really need to know!

A polygon is a simple, closed figure formed by three or more lines.

What you really need to know!

Polygons can be classified by the number of sides they have.

What you really need to know!A diagonal is a line segment in a polygon that joins two nonconsecutive vertices.

What you really need to know!

A regular polygon is a polygon that is equilateral and equiangular.

Example 1:

Classify each polygon:

Pentagon

Heptagon

Example 2:

Find the sum of the measures of the interior angles of a quadrilateral.Key Concept:

If a polygon has n sides, then n – 2 triangles are formed. The sum of the degree measures of the interior angles of the polygon is (n – 2)180.

Example 2:

(n – 2)180

(4 – 2)180

(2)180

360°

Example 3:

A stop sign is a regular octagon. What is the measure of one interior angle in a stop sign?

(n – 2)180

(8 – 2)180

(6)180

1,080° for all 8 angles

135° for one angle

Page 529

Guided Practice

#’s 4-8

Pages 527-529 with someone at home and

study examples!

Read:

Homework: Pages 530-531

#’s 9-20, 23-28, 31-33, 36, 37, 44-53

Lesson Check 10-6

Page

749

Lesson 10-6