Show that, for a triangle with circumradius , semiperimeter , and angles , , and , 4R…

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

Problem

Show that, for a triangle with circumradius RR, semiperimeter ss, and angles AA, BB, and CC, 4Rcos⁡A2cos⁡B2cos⁡C2=s.4R\cos\frac{A}{2}\cos\frac{B}{2}\cos\frac{C}{2}=s.

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