SOLUTION: determine general solution in radians for sin(2x)sinx=cos^2x

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Question 944123: determine general solution in radians for sin(2x)sinx=cos^2x
Answer by lwsshak3(11628) About Me  (Show Source):
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determine general solution in radians for sin(2x)sinx=cos^2x
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sin(2x)sinx=cos^2x
2sinxcosxsinx=cos^2x
2sin^2x=cosx
2(1-cos^2x)=cosx
2-2cos^2x=cosx
2cos^2x+cosx-2=0
solve for cosx by quadratic formula:
cosx+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+
a=2, b=1, c=-2
ans:
cosx=-1.28 (reject)
or
cosx=0.78
x=0.68 radians