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Homework Help: Conics: The Ellipse - Practice

  1. Mar 4, 2005 #1
    Problem I:

    (The coeffiecients throw me off, I don't know what I'm supposed to do with them)
    9x^2 + 16y^2 = 144

    a) coodinates of the centre
    b) lengths of the major and minor axes

    Problem II:

    Sketch a graph of the ellipse

    4x^2 + (y+1)^2 = 9

    PS: For future posts would it be of any help to include the textbook refered to etc?

    In this case:

    Mathpower 12: WE
    Problem I - p. 150 #9
    Problem II - p. 150 #19

    PPS: I've also italicized any comments about my attemts - since people seem to like to help out people making an attempt.
    Last edited: Mar 4, 2005
  2. jcsd
  3. Mar 4, 2005 #2
    You have to get it in standard form first. Divide both sides by 144.

    That gives:

    [tex]\frac{x^2}{16} + \frac{y^2}{9} = 1[/tex]

    a = length of the major axis
    b= length of the minor axis
  4. Mar 5, 2005 #3
    The clue in both the exercises is to recognize the form of an ellipse with its centre in the origin:

    [tex]\frac{x^2}{a^2} + \frac{y^2}{b^2} = 1[/tex]

    As mentioned a and b are the lengths of the axes.

    In the second exercise the centre is not in origo but (x=0,y=-1).
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