Question 810781: Find sin (2 theta)
Given: csc theta = 9/7, theta is in quadrant 2
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! Find sin (2 theta)
Given: csc theta = 9/7, theta is in quadrant 2
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y is positive in QII ; x is negative in QII
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csc = r/y = 9/7 implies that r = 9 and y = 7
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Then x = -sqrt[9^2+7^2] = -sqrt(130)
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cos(t) = x/r = -sqrt(130)/9
sin(t) = y/r = 7/9
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Your Problem:
sin(2 t) = 2*sin(t)*cos(t) = 2*(7/9)(-sqrt(130)/9 = -14sqrt(130)/81
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Cheers,
Stan H.
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