Prove that 55^ + 65^ + 175^ = 0.

MATHEMATICS · Subjective · A Level · Mathematics · Trigonometry · Trigonometry

Problem

Prove that cos⁡55∘+cos⁡65∘+cos⁡175∘=0.\cos 55^\circ + \cos 65^\circ + \cos 175^\circ = 0.

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