Education Technology

SA and NT: Trigonometric Identities

by Texas Instruments

Overview

1.4 Trigonometric Functions

Students will verify, prove, and explore trigonometric identities symbolically, numerically, and graphically.

Key Steps

  • Image

    Students will use the VERITRIG program to help prove the two trigonometric identities. They will use the Text tool to label a triangle drawn within the unit circle. Then students will write x and y in terms of cosθ and sinθ to prove the identity cos2θ + sin2θ = 1.

  • Image

    Students then prove the identity sec2θ = 1 + tan2θ using similar triangles and ratios.

  • Image

    After proving the identities, students can use the cosine and sine values of the angles in the unit circle to prove that the proof holds for each identity.