SOLUTION: Cos x - 2sin^2x=1 find all real numbers that satisfy the equation

Question 809692: Cos x - 2sin^2x=1 find all real numbers that satisfy the equation

Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
Cos x - 2sin^2x=1 find all real numbers that satisfy the equation
Cos x - 2sin^2x = 1
cos(x) - 2(1-cos^2(x)) = 1
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cos(x) - 2 + 2cos^2(x) = 1
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Rearrange:
2cos^2(x) + cos(x) - 3 = 0
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Factor::
(2cos(x) +3)((cos(x)-1) = 0
============
cos(x) = -3/2 or cos(x) = 1
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Note:: cos(x)= -3/2 is extraneous.
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x = 0
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Cheers,
Stan H.
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