Education Technology

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

TI-Nspire™
TI-Nspire™ CAS

3.9

# Precalculus: The Unit Circle

by Texas Instruments

#### Objectives

• Students will describe the relationship between the unit circle and the sine and cosine functions.
• Students will describe the shape of the sine and cosine curves after unwrapping the unit circle.

#### Vocabulary

• continuous function
• periodic function
• unit circle

#### About the Lesson

This lesson involves using a slider to change the measure of the central angle of a unit circle and making connections with right triangle trigonometry.
As a result, students will:

• Discover the relationships between the right triangle and the line segments creating the sine and cosine functions.
• Observe that as the measure of the central angle changes line segments representing the length of a highlighted leg of the right triangle in the unit circle appear on the screen.
• Need prerequisite knowledge of right triangle trigonometry and continuous functions.