Precalculus: Proof of Identities

Objectives

• Students will be able to interpret reciprocal, negative angle, cofunction, and Pythagorean identities in terms of the graphs of the trigonometric functions involved.
• Students will be able to prove trigonometric identities algebraically.
• Students will be able to visualize trigonometric identities graphically.

Vocabulary

• Cofunction Identities
• Identity
• Negative Angle Identities
• Pythagorean Identities
• Reciprocal Identities
• Trigonometric Identities

About the Lesson

This lesson involves discovering, visualizing, and proving trigonometric identities.
As a result, students will:

• Manipulate the graphs of trigonometric functions.
• Utilize sliders to discover and support trigonometric identities.
• Drag a point to see its relationship to its reflected image and use this information to discover the Negative Angle Identities.
• Utilize the relationship between an angle and its complement to discover the Cofunction Identities.