1. The problem statement, all variables and given/known data sin5xcos3x=sin4xcos4x+sinxcosx, solve the identity 2. Relevant equations all the identities and formulas mentioned in my last thread. 3. The attempt at a solution Alright so I thought I could use the product to sum formula on the left side which ended up being 1/2sin10x then I used the sum/difference formula on the right side and got sin5x. Now according to my calculator these are not the same, so where have I gone wrong?