Trigonometric Identities


This chapter opens with two sections on using the Law of Sines and Law of Cosines to solve oblique triangles. The middle of the chapter introduces a variety of identities and explains how some of them can be verified and used. The last part of the chapter covers the solving of trigonometric equations.

What you can expect to learn

After completing these activities you should be able to:

  1. Find a side length or angle measure using the Law of Sines or Law of Cosines.
  2. Determine which expressions are identities.
  3. Identify a sum or difference identity and use one of these to find the exact value of a trigonometric expression.
  4. Find the primary solutions to a trigonometric equation.
Activity List