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Category: Trigonometry

Solve-2cos-x-cos-2x-cos-pi-3-3x-

Question Number 129070 by benjo_mathlover last updated on 12/Jan/21 Solve2cosxcos2x=cos(π33x) Answered by liberty last updated on 12/Jan/21 2cosxcos2x=cos(π33x)cos3x+cosx=12cos3x+32sin3x$$\:\Leftrightarrow\:\mathrm{cos}\:\mathrm{x}\:=\:\frac{\sqrt{\mathrm{3}}}{\mathrm{2}}\:\mathrm{sin}\:\mathrm{3x}−\frac{\mathrm{1}}{\mathrm{2}}\mathrm{cos}\:\mathrm{3x}\: \