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how to prove a(cosB+cosC)=2(b+c)sin^2A/2

siddhant sushil ghadse , 14 Years ago
Grade 11
anser 1 Answers
SAGAR SINGH - IIT DELHI

Dear student,

Use cosine law

cosB=a2+c2-b2/2ac

cosC=a2+b2-c2/2ab

Now prove LHS=RHS

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Last Activity: 14 Years ago
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