Education Technology

Circumscribing a Circle About a Triangle

Activity Overview

In this activity, students use the distance of the circumcenter of a triangle to each vertex of the triangle as the radius and draw a circle using the circumcenter as the center. 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 23-24 from the attached PDF file for your class
  • During the Activity

    Distribute the pages to your class.

    Follow the Activity procedures:

  • Send the figure from Activity 9 saved as an APP VAR via the TI-Navigator

  • Draw a triangle
  • Draw the perpendicular bisector of each side of the triangle
  • Locate the circumcenter
  • Find the distance from the circumcenter to a vertex of the triangle
  • Draw the circumcircle of the triangle
  • After the Activity

    Review student results:

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