Education Technology

Equations of Circles

Activity Overview

In this activity, students will explore the relationship among the location of the center of the circle, the radius of a circle, and the equation of a circle in a plane. They will also investigate the relationship between the points inside, on, and outside a circle, and the equation of the circle.

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 197 - 198 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 circle in the coordinate plane and identify its equation, center, and radius
  • Investigate any relationships that exists between the radius, the coordiantes of the center, and the equation of a circle
  • Construct another circle inside the first one
  • Drag points inside the first circle and the relationship between the equations of the two circles
  • After the Activity

    Review student results:

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