1. The problem statement, all variables and given/known data $$sinx - cosx = 1/3$$ solve for $$sin(2x)$$ 2. Relevant equations $$sin^2x + cos^2x = 1$$ $$sin2x = 2cosxsinx$$ 3. The attempt at a solution I think you can square both sides and get: $$sin^2x - cos^2x = 1/9$$ But how can I use this information to solve for sin2x? Is there a relation/identity between sin2x and sin^2x? But I am unsure of what to do proceeding this point, is there any calculus needed here? It's in my Calculus review problems so I am confused.