Education Technology

# Activities

• ##### Subject Area

• Math: Geometry: Quadrilaterals and Polygons

9-12

45 Minutes

• ##### Device
• TI-Nspire™ CX/CX II
• TI-Nspire™ CX CAS/CX II CAS
• TI-Nspire™ Navigator™
• ##### Software

TI-Nspire™
TI-Nspire™ CAS

3.9

## Sum of Exterior Angles of Polygons

#### Activity Overview

Investigate interior angles of polygons and the sum of their measures.

#### Objectives

• Determine that the interior angle of a polygon and an exterior angle of a polygon form a linear pair (i.e., the 2 angles are supplementary)
• Determine that if one exterior angle is drawn at each vertex of a convex polygon, then the sum of the measures of those exterior angles is 360°
• Determine a formula for the measure of one exterior angle of a regular polygon and use this to discover an alternative form for the formula that is typically used to calculate the measure of the interior angle of a regular polygon

#### Vocabulary

• exterior angle of a polygon
• regular polygon
• irregular polygon
• interior angle of a polygon