Trigonometry

 
Section 7.4

 Derivation of the identity for cosine of a sum

 Derivation of the identity for cosine of a difference

 Derivation of sine identities & an example to help with homework exercises 9-20

 Example to help with exercises 21-30 and derivation of tan(A + B) identity

 Examples to help with homework exercises 31-36

 Another approach to previous problem & example to help with hw exercises 39-48

 Solution to homework exercise 56