SOLUTION: How do you determine if this is correct? Is sin2xsinx-cosx = -(3root3)/2 true for 7pi/6? Explain

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Question 889336: How do you determine if this is correct?
Is sin2xsinx-cosx = -(3root3)/2 true for 7pi/6? Explain
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
PLug in the value and see.
sin%28%287pi%29%2F3%29=sqrt%283%29%2F2
sin%28%287pi%29%2F6%29=-1%2F2
cos%28%287pi%29%2F6%29=-sqrt%283%29%2F2
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sin%282x%29sin%28x%29-cos%28x%29=%28sqrt%283%29%2F2%29%28-1%2F2%29-%28-sqrt%283%29%2F2%29
sin%282x%29sin%28x%29-cos%28x%29=%28sqrt%283%29%2F2%29%28-1%2F2%2B1%29
sin%282x%29sin%28x%29-cos%28x%29=%28sqrt%283%29%2F2%29%281%2F2%29
sin%282x%29sin%28x%29-cos%28x%29=highlight%28sqrt%283%29%2F4%29