Question 864231:  "Find sin theta/2 given that sin theta=-15/17, 
where pi is less than theta is less than 3pi/2." 
 Answer by stanbon(75887)      (Show Source): 
You can  put this solution on YOUR website! "Find sin theta/2 given that sin theta=-15/17, 
where pi is less than theta is less than 3pi/2." 
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Form:: sin(x/2) = sqrt[(1-cos(x))/2 
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Since sin = y/r, y = -15 ; r = 17 
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In QIII x is negative. 
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x = -sqrt[17^2-15^2] = -8 
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Then cos(t) = -8/17 
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Ans: sin(t/2) = sqrt[(1-(-8/17))/2] = sqrt[25/34] = 5/sqrt(34) 
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Cheers, 
Stan H. 
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