Math Analysis

Find the exact value of cos(x/2) if sin x = 3/4 and x is in quadrant II.

==> I got �ã(4-�ã7)/2. Is this correct?

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asked by Emily
  1. I can't read your symbols, but

    if sinx = 3/4 in II then
    cos x = -√7/4

    cosx = 2cos^2 (x/2) - 1
    -√7/4 + 1 = 2cos^2 (x/2)
    (4-√7)/8 = cos^2 (x/2)

    cos x/2 = √[(4-√7)/8]

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    posted by Reiny
  2. Oops, yeah those were supposed to be radicals :) thanks so much!!!!

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    posted by Emily

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