1. The problem statement, all variables and given/known data We are supposed to prove that sin(x+y) = cos(x)sin(y) + sin(x)cos(y) 2. Relevant equations cos(A-pi/2) - sin(A) sin(pi/2 - A) = Cos(A) sin(A-pi/2) = -cos(A) 3. The attempt at a solution We had to prove all of the relevant equations but were allowed to work in groups and now that I am alone, I am just having trouble pushing off and getting started. If someone can give me a push in the right direction, I feel like I will be able to finish it on my own. Thank you in advance.