SOLUTION: Given cos&#952;={{{1/4}}} and 270° < &#952; < 360° degrees, find sin2&#952; exactly.

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Question 965646: Given cosθ=1%2F4 and 270° < θ < 360° degrees, find sin2θ exactly.
Answer by Edwin McCravy(20062) About Me  (Show Source):
You can put this solution on YOUR website!
Given cosθ=1%2F4 and 270° < θ < 360° degrees, find sin2θ exactly 
Since cos%28theta%29=x%2Fr, we draw x = numerator of 1%2F4, which is 1,
and r = the denominator of 1%2F4, which is 4. Since 270° < θ < 360°, θ is in
the 4th quadrant, we draw angle θ in the 4th quadrant like this, with the
red arc indicating angle θ:



sin%282theta%29=2sin%28theta%29cos%28theta%29
sin%282theta%29=2%28y%2Fr%29%28x%2Fr%29
sin%282theta%29=2%28-sqrt%2815%29%2F4%29%281%2F4%29
sin%282theta%29=-2sqrt%2815%29%2F16
sin%282theta%29=-sqrt%2815%29%2F8

Edwin