Further Pure 2: complex numbers and matrices (eigenvalues) – Further Mathematics notes (Cambridge A Level)

(cos θ + i sin θ)ⁿ = cos nθ + i sin nθ; expressing cos nθ and sin nθ in powers of cos θ and sin θ; expressing powers (e.g. sin⁵θ) in multiple angles using z ± 1/z; summing series with complex exponentials.