Use De Moivre's theorem to prove that .

MATHEMATICS · Subjective · IB Diploma Programme · Mathematics: Analysis and Approaches · Number and Algebra · Number and Algebra

Problem

Use De Moivre's theorem to prove that cos⁡3x≡4cos⁡3x−3cos⁡x\cos 3x \equiv 4\cos^3 x - 3\cos x .

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