1. Double 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. Double Angle Formulas Objectives Know the double 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 Double-Angle Identities

3. Quick Check Solve

4. Double Angle Identities

5. Using the Double Angle Formula

7. You Try

9. Verify Trigonometric Identity

10. You Try

11. Conclusions Summary Verify that Sin2x cosx – cos2x sinx = sinx is an identity. Assignment Double Angle Formulas – Page 453 – #(8-12,21-23,28-30)