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Math Help - Trig 2

  1. #1
    Member >_<SHY_GUY>_<'s Avatar
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    Question Trig 2

    another two that i am stuck:

    cos4x-7cos2x=8 with interval [0,2pi)

    and tan^2(theta) + Tan (theta) -12 with the same interval.
    for this one i have so far:

    tan=-4 and tan=3 meaning they are not special right triangles...so i have to use the calculator...but my teacher said that theres a way to graph it and the points of intersection are the answers
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  2. #2
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    \cos(4x) = \cos^{2}(2x) - \sin^{2}(2x)

    \cos(4x) = 2\cos^{2}(2x) - 1

    \cos(4x) = 1 - 2\sin^{2}(2x)

    One of these will help you.
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