Education Technology

# Activities

• ##### Subject Area

• Math: Geometry: Reasoning
• Math: Geometry: Triangles

9-12

40 Minutes

• ##### Device
• TI-83 Plus Family
• TI-84 Plus
• TI-84 Plus Silver Edition
• TI-84 Plus C Silver Edition
• TI-84 Plus CE
• ##### Software

TI Connect™
TI Connect™ CE

• ##### Accessories

TI Connectivity Cable

## Interior & Exterior Angles of a Triangle

#### Activity Overview

Students measure interior and exterior angles of a triangle and make conjectures about their relationships.

#### Key Steps

• Students should construct a triangle using the Triangle tool and label the vertices A, B, and C.

• With Cabri™ Jr., students construct a triangle and measure the three interior angles. With the Calculate tools they make a conjecture about the sum of the angles for all triangles, acute, obtuse, and right.

• Using the triangle students have already constructed, they will construct a line and measure the exterior angle that results from it. Using the Calculate tool again, they will make conjectures about the relationships between interior and exterior angles.