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.

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

Quick Check Solve

Double Angle Identities

Using the Double Angle Formula

You Try

Verify Trigonometric Identity

You Try

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