Use the cosine , sine and tangent sum and difference identities to simplify each of the following:

1.) cos (A + B) + cos (A - B)

2.) cos (A + B) - cos (A - B)

3.) sin (A + B) + sin (A - B)

4.) sin (A + B) - sin (A - B)

5.) tan20degrees + tan32degrees / (1- tan 20degrees X tan 32 degrees)

6.) tan 35 degrees - tan 12 degrees / ( 1 + tan 35 degrees X tan 12 degrees)