1. The problem statement, all variables and given/known data Simplify Sin[3θ] (no double angles) 2. Relevant equations Sin[3θ]=Sin[θ+2θ] Sin[α + β] = Sin[α] Cos[β] + Cos[α] Sin[β] Sin[3θ] = 3sinθ - 4sin^3 θ Cos2θ = 1-2Sin^2θ 3. The attempt at a solution Sin[3θ] = sin[θ+2θ] Sin[θ+2θ] = Sinθ Cos2θ + Cosθ Sin2θ Sinθ Cos2θ + Cosθ Sin2θ = Sinθ (1-2Sin^2θ) + Cosθ Sin2θ =Sinθ - 2Sin^3θ + Cosθ Sin2θ This is where i get lost...I know it should end up being = (3sinθ - 4sin^3 θ) but i cannot figure out how to get there. I don't know whether I just dont have the formula i need or what.