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Solve the equation 8 cos^2 X -2 =0 given that 180< or equal to X <or equal to 360 degrees.

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    8cos^2X - 2 = 0
    8cos^2x = 2
    cos^2x = 2/8 = 0.25
    cosx = sqrt(0.25) = 0.5
    Xr = 60o = Reference angle.

    X-Xr = 180
    x-60 = 180
    X = 180+60 = 240o.

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