Math, asked by lait4e0juakshu, 1 year ago

A cos A + b cos B + c cos C = 2a sin B sinC

Answers

Answered by rdahin

a cos A + b cos B + c cos C=2R(sinAcosA+sinBcosB+sinCcosC)
(∵a=2RsinA b=2R sin B c=2RsinC)
=R (sin2A+sin2B+sin2C)=4RsinAsinBsinC=2asinBsinC
∵sin2A+sin2B+sin2C=4sinAsinBsinC

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