Education Technology

# Activities

• ##### Subject Area

• Math: Precalculus: Trigonometry (Triangle and Circular Functions)

9-12

110 Minutes

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

## Approximation of Pi Using an Area Model

#### Activity Overview

Students will approximate pi by setting up trigonometric ratios and calculating the areas of regular polygons inscribed within and circumscribed about a circle.

#### Before the Activity

I use the "Approximation of Pi Using Archimedes' Method" activity first. This activity follows the same format. After doing the first activity, the students can usually do this activity rather quickly.

#### During the Activity

Have the students draw a 30-60-90 triangle in the first diagram, with the hypotenuse extending from the center of the circle to a vertex of the triangle. Define an angle theta as a central angle of the circle.

#### After the Activity

Question #8 leads into a great introduction of limits.