SOLUTION: prove that : 2 (cos^2)A+ cos A

SOLUTION: prove that : 2 (cos^2)A+ cos A - 1 = 0

Question 921419: prove that :
2 (cos^2)A+ cos A - 1 = 0
Found 2 solutions by stanbon, Alan3354:
Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
2 cos^2(A)+ cos(A) - 1 = 0
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Factor:
(2cos(A)-1)(cos(A)+1) = 0
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cos(A) = 1/2 or cos(A) = -1
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A = +/- 60 degrees OR A = 180 degrees
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Cheers,
Stan H.
Answer by Alan3354(69443) (Show Source): You can put this solution on YOUR website!
It doesn't

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