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Math Help - Quadratic Trig Functions

  1. #1
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    Quadratic Trig Functions

    We're learning how to solve quadratic trigonometric equations:

    ex. 3sin^2x - 8sinx -3 = 0
    (3sinx+1)(sinx-3) = 0
    then go on from there...

    but how do I solve this one?

    cotxcosx=cosx ?

    Do I sub in 1/tanx for cot x ? where do I go from there?

    Id appreciate some help
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  2. #2
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    Quote Originally Posted by mayflower29 View Post
    We're learning how to solve quadratic trigonometric equations:

    ex. 3sin^2x - 8sinx -3 = 0
    (3sinx+1)(sinx-3) = 0
    then go on from there...

    but how do I solve this one?

    cotxcosx=cosx ?

    Do I sub in 1/tanx for cot x ? where do I go from there?

    Id appreciate some help
    I typically get them into a form where there are only sines and cosines, but for this one:
    cot(x)cos(x) = cos(x)

    cot(x)cos(x) - cos(x) = 0

    (cot(x) - 1)cos(x) = 0

    Means that
    cot(x) - 1 = 0
    or
    cos(x) = 0

    -Dan
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  3. #3
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    Thanks a lot!
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