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Homework Help: Conics (ellipse)

  1. May 15, 2012 #1
    1. The problem statement, all variables and given/known data
    Given the vector (6,-15) and foci (6,10) (6,-14),
    Find the equation of the conic.

    2. Relevant equations

    Vector = <6,-15>
    (x-h)2/a2 + (y-k)2/b2 = 1

    Foci (h+c,k) and (h-c,k)
    vertices (h+a,k), (h-a,k)

    3. The attempt at a solution
    k = 6

    I'm not sure what I'm doing. How do I know that this conic is an ellipse, and not a hyperbola? And how do I find b and c, after finding a?

    How does a vector even relate to the equation of an ellipse?
    Last edited: May 15, 2012
  2. jcsd
  3. May 15, 2012 #2


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    Staff Emeritus
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    I assume the point (6, -15) is a point on the ellipse.

    The expressions you've written down for the locations of the foci are for when the foci lie on the same horizontal line. In this case, the foci lie on the same vertical line.

    Your value for a is wrong.
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