I have to express: cos 6θ and sin 6θ in terms of sinθ and cosθ.
I tried to do it using Demoivre's formula but it looks horribly wrong
I got: (cosθ + sinθ)^6
any assistance would be appreciated.
De Moivre's formula says that . Expand the right side by the binomial theorem. Then take the real part to get . Taking the imaginary part yields a similar formula for .