Education Technology

# Activities

9-12

60 Minutes

• ##### Device
• TI-89 / TI-89 Titanium
• TI-92 Plus / Voyage™ 200

TI Connect™

• ##### Accessories

TI Connectivity Cable

• ##### Other Materials
This is Activity 2 from the EXPLORATIONS Book:
Geometric Investigations on the Voyage 200 with Cabri

## Investigating Properties of Trapezoids

#### Activity Overview

Students draw trapezoids and investigate their properties. They derive the area formula for a triangle from the area formula for a trapezoid. They also investigate the terms: Isosceles trapezoid and Tessellation.

#### Before the Activity

• See the attached PDF file for detailed instructions for this activity
• Print page 5 from the attached PDF file for your class
• #### During the Activity

Distribute the page to the class.

• Determine 3 ways to draw a trapezoid and drag independent points to ensure that the figure remains a trapezoid
• Note that the sum of all interior angles is 360 degrees
• Find a relationship regarding angle measurement that appears to be true
• Drag the vertex and observe the relationship
• Determine 3 ways to construct an isosceles trapezoid
• Find at least 3 properties that are true for all isosceles trapezoids
• Drag a vertex along the shorter base till its length becomes zero and the trapezoid becomes a triangle
• Explore how the area of the trapezoid can be used to find the area of the triangle
• Find the relationship between midsegment of a trapezoid and a triangle
• Use the Transformation tool to tesselate a trapezoid and observe the figure formed
• #### After the Activity

Review student results:

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