Education Technology

# Activities

• ##### Subject Area

• Math: Geometry: Triangles

9-12

20 Minutes

• ##### Software

Cabri Geometry™

## Angle Theorem

#### Activity Overview

Students use the Cabri Geometry II Plus software to investigate the relationship between angle and ratio in a right triangle.

#### Before the Activity

• Download the Cabri Geometry™ software on the computer

• See the attached FIG file for details of this activity

• #### During the Activity

Follow the Activity procedure:

• Select the multiple animation option from the toolbar
• Animate the number 40 [the angle] and observe the effect on the length of sides and ratio of the side lengths
• Note that as the angle increases, the length of base decreases, the height increases, while the hypotenuse retains its length
• Observe that as the angle increases, the ratio of the opposite side to the hypotenuse increases, and the ratio of the adjacent side to the hypotenuse decreases
• Recognize the fact that sin 90° = 1
• #### After the Activity

Review student results:

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