Solve cos 2x – 3sin x cos 2x = 0 for the principal value(s) to
two decimal places.

Please explain.

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  1. cos2x (1 - 3sinx) = 0
    cos2x = 0 or sinx = 1/3

    cos 2x = 0:
    2x = k*pi/2 where k is an integer
    x = pi/4, 3pi/4, 5pi/4, 7pi/4

    sinx = 1/3:
    x = 0.34 or pi-0.34

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