# Activities

• ##### Download

• • ##### Subject Area

• Math: Geometry: Transformational Geometry
• Math: Geometry: Triangles

• ##### Author 9-12

40 Minutes

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

TI Connect™

• ##### Accessories

TI Connectivity Cable
Unit-to-Unit link cables

## Reflecting a Triangle in the Coordinate Plane

#### Activity Overview

In this activity, students use the drawing and measurement tools of Cabri™ Jr. to blend coordinate geometry with drawing tools. They visualize symmetry and reflect a point across the y-axis. NCTM Geometry Standards: Specify locations and describe spatial relationships using coordinate geometry and other representational systems. Apply transformations and use symmetry to analyze mathematical situations.

#### 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
• Set up the TI-Navigator™ system
• See the attached PDF file for detailed instructions for this activity
• Print pages 46 - 47 from the attached PDF file for your class
• #### During the Activity

Distribute the pages to your class.

Follow the Activity procedures:

• Draw a triangle
• Find the coordinates of the triangle
• Reflect the triangle across the y-axis
• Find the coordinates of the reflected triangle
• Explore the relationship between the original coordinates and the coordinates of the reflected triangle

• TI-Navigator activity:
• Load a background image of a triangle in Quadrant 1
• Have students mark a point on the triangle then mark a second point which is the image of the first point reflected across the y-axis
• #### After the Activity

Review student results:

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