SOLUTION: Let Cos X=3/4 with X in QIV, find Cot 2x

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Question 1074733: Let Cos X=3/4 with X in QIV, find Cot 2x
Answer by Alan3354(69443) About Me  (Show Source):
You can put this solution on YOUR website!
Let Cos t=3/4 with t in Q4, find Cot 2t
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cos(t) = x/r = 3/4
sin = y/r
y = sqrt(r^2 - x^2) = sqrt(7)
sin(t) = -sqrt(7)/4 *** sine negative in Q4 ***
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sin(2t) = 2sin(t)cos(t) = -3sqrt(7)/8
cos(2t) = sqrt(1 - sin^2(2t)) = 1/8 *** cosine + in Q4 ***
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cot = cos/sin = -1/3sqrt(7)
cot%282t%29+=+-sqrt%287%29%2F21