Match each expression with the correct sum-to-product identity.

List 1

1. sinC+sinD

2. sinC-sinD

3. cosC+cosD

4. cosC-cosD

List 2

1. 2cos((C+D)/2)sin((C-D)/2)

2. -2sin((C+D)/2)sin((C-D)/2)

3. 2sin((C+D)/2)cos((C-D)/2)

4. 2cos((C+D)/2)cos((C-D)/2)