Question 1000161: If sin theta = 2/3, theta lies in quadrant II then sin2 theta =
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! If sin theta = 2/3, theta lies in quadrant II then sin2 theta =
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In QII, x is negative and y is positive
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By definition, sin = y/r; so, y = 2 and r = 3
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Then x = -sqrt[3^2-2^2] = -sqrt(5)
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sin = 2/3
cos = x/r = -sqrt(5)/3
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Ans: sin(2*theta) = 2sin(t)*cos(t) = 2(2/3)(-sqrt(5))/3 = -4sqrt(5)/9
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Cheers,
Stan H.
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