1. 5.1 Fundamental Identities
Statements like “ ” and “ ” are trigonometric identities because they are true for all values of the variable for which both sides of the equation are defined.
The set of all such values is called the domain of validity of the identity.
Basic Trigonometric Identities
Some trigonometric identities follow directly from the definitions of the six basic trigonometric functions.
These basic identities consists of the reciprocal identities and the quotient identities.

2. Basic Trigonometric Identities
Reciprocal Identities

3. Basic Trigonometric Identities
Quotient Identities

4. Basic Trigonometric Identities
Pythagorean Identities

5. Using Identities
Find and if and

6. Cofunction Identities

7. Odd-Even Identities

8. Using More Identities
If , find

9. Simplifying by Factoring and Using Identities
Simplify the expression

10. Simplifying by Expanding and Using Identities
Simplify the expression

11. Simplifying by Combining Fractions and Using Identities
See Example 5 on p. 448 – 449.

12. Solving a Trigonometric Equation
See Example 6 and Example 7 on p. 449 – 450.

13. More Practice!!!!!
Homework – Textbook p. 451 – 452 #1 – 31 ODD.