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Math Help - Ellipse! help!

  1. #1
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    Red face Ellipse! help!

    Hi there!
    um.. I am having trouble with a question I started some work and then I am not sure if I am doing it right! and if I am I don't know what to do next!

    anyways here is the question that stumps me!
    An ellipse is formed by strecthing the grapgh of x^2+ y^2=1 horizontally by a factor of 3 and vertically by a factor of 4. Determine the equation of this ellipse in standard form.

    so my work:
    x^2+ y^2=1
    (x/3)^2 +(y/4)^2=1

    x^2/9 + y^2/16=1

    am I going on the right track or am I totally off? if I am doing this right were do I go from here?
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  2. #2
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    Quote Originally Posted by cutie4ever View Post
    Hi there!
    um.. I am having trouble with a question I started some work and then I am not sure if I am doing it right! and if I am I don't know what to do next!

    anyways here is the question that stumps me!
    An ellipse is formed by strecthing the grapgh of x^2+ y^2=1 horizontally by a factor of 3 and vertically by a factor of 4. Determine the equation of this ellipse in standard form.

    so my work:
    x^2+ y^2=1
    (x/3)^2 +(y/4)^2=1

    x^2/9 + y^2/16=1

    am I going on the right track or am I totally off? if I am doing this right were do I go from here?
    The graph,
    x^2+y^2=1
    The radius is 1 of the circle.

    If you stretch the x-axis by 3 you then have a semi-axis along x to be 3. Similarly for the y axis.
    In that case the equation of the ellipse is,
    \frac{x^2}{3^2}+\frac{y^2}{4^2}=1
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  3. #3
    Senior Member TriKri's Avatar
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    If a is the width of the elipse, and b is the height, the elipse equation is \frac{x^2}{a^2}+\frac{y^2}{b^2} = 1.
    Last edited by ThePerfectHacker; November 22nd 2006 at 03:56 PM.
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