Education Technology

Centers of a Triangle

Published on 06/09/2008

Activity Overview

The centroid, circumcenter, orthocenter, and incenter are the four classic centers of a triangle that are studied in geometry. In this activity, you will construct these center points and discover their properties.

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
  • Use the TI-Navigator™ to transfer the attached Cabri Jr. AppVar files to each calculator
  • See the attached PDF file for detailed instructions for this activity
  • Print pages 117 - 120 from the attached PDF file for your class
  • During the Activity

    Distribute the pages to your class.

    Follow the Activity procedures:

  • Use the AppVar to go directly to the exploration section
  • Construct a triangle and its centroid
  • Construct a triangle and its circumcenter
  • Construct a triangle and its orthocenter
  • Construct a triangle and its incenter
  • Investigate the properties of the figures drawn
  • Drag the vertices and sides of the triangle and observe the changes that the figures undergo
  • After the Activity

    Review student results:

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