Activity Overview
Students use the Cabri™ Jr. application to draw triangles and construct perpendicular bisectors on the sides of a triangles. They study the properties of a triangle and understand how the measures of angles of a triangle is always 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 - 19 from the attached PDF file for your class
During the Activity
Distribute the pages to the class.
Follow the Activity procedures:
Construct an acute scalene triangle and label its vertices
Measure the angles of the triangle
Construct three perpendicular bisectors on each of the sides of the triangle
Determine the point of intersection of the perpendicular bisectors
Hide the perpendicular bisectors and display only the intersection point
Make conjectures about the intersection of the perpendicular bisectors of a triangle when the triangle is acute, right, or obtuse
Calculate the sum of measures of the angles of the triangle
Move a vertex and observe the change in the measure of the angles
After the Activity
Review student results:
As a class, discuss questions that appeared to be more challenging
Re-teach concepts as necessary