SOLUTION: find cos x/2, given: sin x = 1/4, 360 < x < 450, use half-angle identity to find the exact value.

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Question 453317: find cos x/2, given: sin x = 1/4, 360 < x < 450, use half-angle identity to find the exact value.
Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
find cos x/2, given: sin x = 1/4, 360 < x < 450
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cos(x/2) = +/- sqrt[(1+cos(x))/2]
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Since sin(x) = 1/4, y = 1 and r = 4
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So x = sqrt[4^2-1^2] = sqrt(15)
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Therefore cos(x) = x/r = sqrt(15)/4
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So, cos(x/2) = +/- sqrt[(1+[sqrt(15)/4]]/2]
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Cheers,
Stan H.
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