Education Technology

# Activities

• ##### Subject Area

• Math: Geometry: Circles
• Math: Geometry: Triangles

9-12

30 Minutes

• ##### Device
• TI-83 Plus Family
• TI-84 Plus
• TI-84 Plus Silver Edition

TI Connect™

• ##### Accessories

TI Connectivity Cable
Unit-to-Unit link cables

## Exploring the Circumcenter of a Triangle

#### Activity Overview

In this activity, students develop an understanding of the circumcenter of a triangle. Students construct perpendicular bisectors of three sides of a triangle and find the circumcenter. NCTM Geometry Standard covered: Analyze characteristics and properties of 2- and 3-dimensional geometric shapes and develop mathematical arguments about geometric relationships.

#### Before the Activity

• Install the Cabri Jr. App on the students' graphing calculators using TI Connect™, a TI Connectivity Cable, and the Unit-to-Unit Link Cable
• Set up the TI-Navigator™ system
• See the attached PDF file for detailed instructions for this activity
• Print pages 17-18 from the attached PDF file for your class
• #### During the Activity

Distribute the pages to your class.

Follow the Activity procedures:

• Draw a triangle
• Draw the perpendicular bisector of each side of the triangle
• Find the circumcenter, which is the point where all the bisectors intersect
• Explore properties of the circumcenter

• TI-Navigator activity:
• Save this file as an APP VAR for later exploration and investigation. (Activity 13)
• #### After the Activity

Review student results:

• As a class, discuss questions that appeared to be more challenging
• Re-teach concepts as necessary