Product-to-Sum and Sum-to-Product Formulas

Product-to-Sum Formulas Changing an equation from a multiplication problem to an addition problem

Expressing Products as Sums Express each of the following products as a sum containing only sines or cosines. (a) sin (6q) sin (4q) (b) cos (3q) cos (q)

Expressing Products as Sums (c) sin (3q) cos (5q)

Sum-to-Product Formulas Changing equations from an addition problem to a multiplication problem

Expressing Sums as a Product Express each sum or difference as a product of sines and/or cosines. (a) sin (5q) – sin (3q) (b) sin (4q) + sin (2q)

Expressing Sums as Products (c) cos q – cos (3q) (d) cos (5q) + cos (3q)

Establishing Identities Establish the identity

Establishing Identities Establish the identity

Product-to-Sum and Sum-to-Product On-line Tutorial On-line Video