Education Technology

# Activities

• ##### Subject Area

• Math: Geometry: Triangles

9-12

90 Minutes

• ##### Device
• TI-83 Plus Family
• TI-84 Plus
• TI-84 Plus Silver Edition

TI Connect™

• ##### Accessories

TI Connectivity Cable

• ##### Other Materials
This is Activity 15 from the EXPLORATIONS Book:
Cabri™ Jr.: Interactive Geometry Activities and Investigations.

## Similar Triangles and Proportions

#### Activity Overview

In this activity, students will investigate the relationship among the similar triangles formed when a segment is constructed parallel to one side of a triangle. They will explore the various ratios that exist between the lengths of the sides of similar triangles.

#### 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 97 - 98 from the attached PDF file for your class
• #### During the Activity

Distribute the pages to your class.

• Use the AppVar to go directly to the exploration section
• Construct a triangle and a line intersecting the triangle that is parallel to one of its sides
• Measure the lengths of the sides of the two similar triangles formed, and investigate any relationships among the ratios of the measured lengths
• #### After the Activity

Review student results:

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