math !!

solve the equation for the interval
0<x<2pie

cos^2 x + 2cosx + 1 = 0

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asked by Amy
  1. cos^2 x + 2cosx + 1 = 0 factors to
    (cos x + 1)^2 = 0
    cos x + 1 = 0
    cos x = -1
    x = PI

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    posted by Reiny

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