Education Technology

Angle Bisectors and Medians of Quadrilaterals

Activity Overview

In this activity, students will construct angle bisectors and medians in quadrilaterals and explore the properties that appear to be true for four-sided figures. They may find it necessary to review the definitions and properties of special quadrilaterals in order to construct the figures.

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 155 - 158 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 parallelogram and its four angle bisector
  • Drag the vertex and /or side of the original parallelogram and observe the new quadrilateral formed by angle bisectors
  • Construct the medians of a generalized quadrilateral
  • Construct the quadrilateral formed by the medians
  • Drag the vertices and\or sides to form a special quadrilateral and note what happens to the quadrilateral formed by the medians
  • Calculate the ratio of the area of the original quadrilateral to the area of the quadrilateral formed by the medians
  • After the Activity

    Review student results:

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