1. Half Angle Formulas T, 11.0: Students demonstrate an understanding of half-angle and double- angle formulas for sines and cosines and can use those formulas to prove and/or simplify other trigonometric identities.

2. Half Angle Formulas Objectives Know the half angle identities Verify more complex trigonometric identities using the basic trigonometric identities, Pythagorean identities, co-function identities, odd/even identities, sum & difference identities, double angle identities, half- angle identities and justify each step in the verification process. Key Words Degrees Radians Half-Angle Identities

3. Quick Check

4. Half Angle Identities Take out your Unit Circle…

5. Using the Half Angle Identity

6. You try

7. Conclusions Summary Name the quadrant in which the terminal side lies – X is a second quadrant angle. In which quadrant does 2x lie? – x/2 is a first quadrant angle. In which quadrant does x lie? Assignment Half Angle Formulas – Page 453 – #(6,7,14-18,33)