6.4Sum and Difference Formulas

Sum and Difference Formulas for Cosines

cos cos cos sin sin

cos cos cos sin sin

(1) Find the exact value of

Theorem Sum and Difference Formulas for Sines

(2)Find the exact value of

Examples 3 - 7

Page 491: 13 – 21 odd

8

Theorem Sum and Difference Formulas for Tangents

(9)Find the exact value of

Cofunction Identities

(10)Establish the identity

Cos (3/2 + ) = sin

(11) Example 10 on p. 490

Assignment

Pages 491 – 492: 2, 10, 12, 18, 20, 22, 28, 30, 34, 64, and 74