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Math Help - Trignomectric Expressions and Equations

  1. #1
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    Trignomectric Expressions and Equations

    solve it for 0<x<360
    4 cos^2x-3=cosec220
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  2. #2
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    I believe that I've got the question noted wrong

    I think you want 4cos^{2}(x)-3=cosec(220) (see e^(i*pi) below)

    The one I noted down is
    4cos^{2}(x-3)=cosec(220)

    Which goes on to have complex solutions - if any exist - which I didn't realise - so I hope you didn't use any of my garbage from before .
    Last edited by rain; November 1st 2009 at 10:50 AM. Reason: Misinterpreting question and writing garbage :(
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  3. #3
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    e^(i*pi)'s Avatar
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    Quote Originally Posted by raza9990 View Post
    solve it for 0<x<360
    4 cos^2x-3=cosec220
    sin(220) < 0

    4cos^2x - (3+cosec220) = 0

    Use the difference of two squares and let u=\sqrt{3+cosec(220)}

    (2cos(x)-u)(2cos(x)+u) = 0


    cos(x) = \frac{1}{2}\sqrt{3+cosec(220)}

    or

    cos(x) = -\frac{1}{2}\sqrt{3+cosec(220)}
    Last edited by e^(i*pi); November 1st 2009 at 08:52 AM.
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