In a triangle ABC, write cos (B+C)/2 in terms of angle A.

1.	In a triangle ABC, write cos (B+C)/2 in terms of angle A.
Answer» It can be written as A+B+C=180. Now divide 2 on both side A+B+C/2=90. B+C/2 =90 - A/2. Apply cos on both side we get. Cos B+C/2=sin A/2 I hope this would help you Cos ( 90 - A /2 )

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