1. 5.5-Multiple Angle Formulas

2. Double Angle Formulas:

3. Ex. 1 Solve the equation:

4. Ex. 2
and Find: 13 5 a)
-12 b)
We could use any of the three formulas for cosine!

5. c) 13 5
-12 12

6. Ex. 3 Rewrite as a sum of two sinx expressions:

7. Ex. 4 Find the value of:

8. Power-Reducing Formulas

9. Ex. 5 Re-write as a sum of first powers of the cosines
of multiple angles:

10. Half-Angle Formulas

11. Ex. 6 Find the value of:
225 is a unit circle value!
Note that:
Why
negative??

13. Ex. 7 Find the exact value of:
210 is a unit circle value!
Note that:
Why positive??