If A+B+C=pi then prove that cos^2 (A/2)+...

If `A+B+C=pi` then prove that `cos^2 (A/2)+cos^2 (B/2)-cos^2 (C/2)=2cos(A/2)cos(B/2)sin(C/2)`

A

`2 cos ""A/2 + cos ^(2) ""B/2 - cos ^(2) ""C/2 `

B

`4 cos ""A/2 cos ""B/2 sin ""C/2`

C

`1-2 cos ""A/2 cos ""B/2 sin ""C/2`

D

`1-4 cos ""A/2 cos ""B/2 sin ""C/2`

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The correct Answer is:

A

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