# Activities

• ##### Download

• • ##### Subject Area

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

• ##### Author 9-12

45 Minutes

• ##### Device
• TI-Nspire™
• TI-Nspire™ CAS
• TI-Nspire™ CX/CX II
• TI-Nspire™ CX CAS/CX II CAS
• TI-Nspire™ Navigator™
• TI-Nspire™ Apps for iPad®
• ##### Software

TI-Nspire™
TI-Nspire™ CAS

3.6

## Radian Measure

#### Activity Overview

This lesson involves exploring the relationship between the central angle, the arc, and the radius of a circle.

#### Objectives

• Students will describe the relationship between a central angle, the radius, and the arc length of a circle.
• Students will recognize that changing the radius of a circle does not affect the proportions in the circle.
• Students will convert an angle measure from radians to degrees and vice versa.

#### Vocabulary

• central angle
• exact value
• radian
• right angle

#### About the Lesson

This lesson involves exploring the relationship between the central angle, the arc, and the radius of a circle.
As a result, students will:

• Use a slider to change the radius, and conclude that the relationships are preserved.
• Form a definition of a radian.
• Drag a point to change the measure of the central angle to discover the relationship between radian and degree measure.
• Create a proportion that can be used to convert the measure of an angle from degrees to radians and vice versa.