Prove the identity

A+B+C= Ï€

prove that

\cot(A/2)+\cot(B/2)+\cot(B/2)=\cot(A/2)\cot(B/2)\cot(C/2)

2 Answers

A/2+B/2+C/2=âˆ©/2

tanâˆ©/2= (tanA/2+tanB/2+tanC/2)-tanA/2tanB/2tanC/2 /[1-(tanB/2tanC/2+tanC/2tanA/2+tanA/2tanB/2)]

hence the denominator is 0

tanB/2tanC/2+tanC/2tanA/2+tanA/2tanB/2=1

multiplying by cotA/2cotB/2cotC/2
\SigmacotA/2=cotA/2cotB/2cotC/2

good work

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