Question 829740: If cotA=12/15 and 0 < A < pi/2, determine the exact value of the following. Sin (2A) cos(2A) sin(A/2) tan(A/2) cos(A/2) I only need one solved so I can find out the process of what to do. My exam is tomorrow morning. Thanks in advance!
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! If cotA=12/15 and 0 < A < pi/2, determine the exact value of the following. Sin (2A) cos(2A) sin(A/2) tan(A/2) cos(A/2) I only need one solved
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Since cot(A) = x/y, x = 12 and y = 15 when A is in QI
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Then r = sqrt[12^2+15^2] = sqrt(369) = 19.21
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So, sin(A) = y/r = 15/19.21 ;
cos(A) = x/r = 12/19.21
tan(A) = y/x = 15/12 = 5/4
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Then sin(2A) = 2sin(A)cos(A) = 2(15/sqrt(369)(12/369) = 360/369
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Cheers,
Stan H.
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