Question 887878: Approximate the solutions (to the three decimal places) of the equation in the given interval.
cos^2 x - 2 cos x - 1 = 0, [0, pi]
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! Approximate the solutions (to the three decimal places) of the equation in the given interval.
cos^2 x - 2 cos x - 1 = 0, [0, pi]
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cos(x) = [2 +- sqrt(4-4*-1)]/2
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cos(x) = [2 +- sqrt(8)]/2
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cos(x) = [1+-sqrt(2)]
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Since -1<= cos(x) <=1,
cos(x) = [1-sqrt(2)/2 = -0.2071
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x = cos^-1(0.2071) = 101.95 degrees
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Cheers,
Stan H.
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