Education Technology

Incenter of a Triangle

Published on 06/09/2008

Activity Overview

In this activity, students observe a special characteristic of the bisectors of the angles in a triangle. They test their conjecture by changing the size and shape of the triangle. 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 15-16 from the attached PDF file for your class
  • During the Activity

    Distribute the pages to your class.

    Follow the Activity procedures:

  • Draw a triangle using the App
  • Draw the bisector of each angle of the triangle
  • Locate the incenter of the triangle
  • Explore properties of the incenter


  • TI-Navigator activity:
  • Save the file and send it to students as an APP VAR for exploration and investigation in Activity 12
  • After the Activity

    Review student results:

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