Posted by Cody on Friday, February 18, 2011 at 5:00pm.
then cosx = -1/√3
x must be in II or III
in II:
sinx = √2/√3
sin 2x = 2sinxcosx = 2(√2/√3)(-1/√3) = -2√2/3
in III:
sinx = -√2/√3
sin 2x = +2√2/3
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