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Math Help - Conic Sections and polar coordinates

  1. #1
    Junior Member
    Joined
    Jan 2010
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    Exclamation Conic Sections and polar coordinates

    Hello

    I'm stuck on this question Word for word from the text
    "A.) decide whether the equation
    \[9x^2+6xy+y^2-12x-4y+4=0\]<br />
    represents a parabola an elipse or a hyberbola
    b.) show that the graph of the equation in part A is the line y=-3x+2

    my problem is that I cannot find the angle, in all the othe questions the angle worked out to be a special triangle but in this one I have tried applying tan 2\alpha =\frac{B}{A-c} but I get an angle of 1/3
    any help would be appreciated
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  2. #2
    MHF Contributor

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    B= 6, A= 9 and C= 1? so tan(2\alpha)= \frac{6}{9- 1}= \frac{3}{4}. arctan(3/4) is about .6435 radians so that \alpha is, indeed, approximately 1/3 radian. What's wrong with that?
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