Question 388642: Please help!
If cos x = 0.8, what is a value of tan 1/2x?
Thanks
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! If cos x = 0.8, what is a value of tan 1/2x?
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tan(x/2) = sin(x)/(1+cos(x))
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If cos(x) = 4/5, x = 4 and r = 5
Then y = sqrt[5^2-4^2] = 3
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So, sin(x) = 3/5
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tan(x/2) = (3/5)/(1+(4/5)) = (3/5)/(9/5) = 1/3
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Cheers,
Stan H.
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