3.2
Proofs for Parts 1-4 require that you only know and use the basic (fundamental) and pythagorean identities:
Prove Basic Trig Identities Part 1: http://www.youtube.com/watch?v=iKWGv0xcuCA
Prove Basic Trig Identities Part 2: http://www.youtube.com/watch?v=cqqpINKly24
Prove Basic Trig Identities Part 3: http://www.youtube.com/watch?v=h6UGBn6cD4c
Prove Basic Trig Identities Part 4: http://www.youtube.com/watch?v=2m0_HXU2AGg