Activity Overview
Students construct a line parallel to the base of a triangle and measure the angles formed. They use the construction to prove that the sum of the measures of the interior angles of a triangle is 180 degrees.
Before the Activity
Install the Cabri™: Jr. App on the students' graphing calculators using one of these two methods:
TI-Connect™, a TI Connectivity Cable, and the Unit-to-Unit Link Cable
TI-Navigator™ "send to class" feature
See the attached PDF file for detailed instructions for this activity
Print pages 1 - 4 from the attached PDF file for your class
During the Activity
Distribute the pages to the class.
Follow the Activity procedures:
Draw a line parallel to the base of a triangle through the top vertex
Measure the angles that are formed by the parallel line and the sides of the triangle
Measure the interior angles of the triangle
Use the figure to prove that the sum of the interior angles of any triangle is 180 degrees
After the Activity
Review student results:
As a class, discuss questions that appeared to be more challenging
Re-teach concepts as necessary