Lesson 1: 5.1 Using Fundamental Identities

How do you rewrite trigonometric expressions in order to simplify and evaluate trigonometric functions?

cofunction identities
even/odd identities

HSF-TF. A - Prove the Pythagorean identity sin2(?) + cos2(?) = 1 and use it to find sin(?), cos(?), or tan(?) given sin(?), cos(?), or tan(?) and the quadrant of the angle.

Use Khan Academy resources.

Students will learn how to recognize the pattern and structure of trigonometric expressions and use the fundamental trigonometric identities in order to rewrite and simplify expressions.

The fundamental trigonometric identities can be used to simplify trigonometric expressions. For instance, you can use trigonometric identities to simplify an expression for the coefficient of friction.

When simplifying expressions, remind students that any new value introduced must be a known trigonometric identity or an algebraic identity. Remind students that they can only use proven fundamental trigonometric identities to simplify expressions.
Students may incorrectly simplify trigonometric expressions due to algebraic errors.

To simplify expressions in the exercises, students will need to use the fundamental trigonometric identities. Instruct them to read each identity aloud so that they can hear how it is used in the expression. Naming each identity as it is implemented will help students better remember the case in which each identity is used.

Use common assessments.

Pre-Calculus with Limits resources.