If the sides be

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

Problem

If the sides be a,b,ca, b, c , then show that acos⁡A+bcos⁡B+ccos⁡C=4Rsin⁡Asin⁡Bsin⁡Ca \cos A + b \cos B + c \cos C = 4R \sin A \sin B \sin C

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