precal 2

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solve the equation 4cos^2x-1=0

  • precal 2 -

    cos^2x = 1/4
    cosx = ± 1/2

    do you know an angle x , so that cosx = 1/2 ???
    and by the CAST rule, isn't that angle in any of the 4 quadrants?

    hint: cos60° = 1/2

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