Trigonometry

 
Section 7.6

 The Product-to-Sum Formulas & an example to help with homework exercises 1-10

 The Sum-to-Product Formulas & an example to help with homework exercises 11-18

 Examples to help with homework exercises 19-36

There is an error in movie 3. In problem 2, change the + sign in the numerator on the right side of the equation to a - sign.