SOLUTION: If cosA = 1/3, find cos(A/2) for acute angle A Show work please.

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Question 1030019: If cosA = 1/3, find cos(A/2) for acute angle A
Show work please.
Answer by robertb(5830) About Me  (Show Source):
You can put this solution on YOUR website!
cos%5E2%28A%2F2%29+=+%281%2BcosA%29%2F2 ==> cos%5E2%28A%2F2%29+=+2%2F3 ==> cos%28A%2F2%29+=+sqrt%282%2F3%29+=+sqrt%286%29%2F3.
Choose the positive value(not the negative!) because A is acute, and hence the angle A in standard position should be in the first quadrant, where cosine is positive.