1. Basic Trigonometric Identities
Section 15.1

2. Recall Basic Trig Identities

3. Pythagorean Identities

4. Strategy for Proving Identities
Separate the equation into a left-side expression and right-side expression and work with these separately.
Simplify the more complicated side, looking for ways to use the basic trig identities
After simplifying one side as much as you can, try working with the other side until both sides are the same.
Worst case scenario: express both sides in terms of sine and cosine. Then, clean up your mess. 

5. EXAMPLE: (note restrictions)
Prove

7. EXAMPLE: (note Restrictions)
Prove

9. EXAMPLE: (note Restrictions)
Prove

11. EXAMPLE: (Note Restrictions)
Prove:

13. Homework:
p , #9-27(odd)