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Math Help - Ellipse

  1. #1
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    Ellipse

    [LEFT]Determine the length of the ray focal of the point M(3,\frac{7}{4}) who is on the ellipse 7x^2+16y^2=112


    Answer:
    \frac{25}{4} and \frac{7}{4}
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  2. #2
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    Quote Originally Posted by Apprentice123 View Post
    [LEFT]Determine the length of the ray focal of the point M(3,\frac{7}{4}) who is on the ellipse 7x^2+16y^2=112


    Answer:
    \frac{25}{4} and \frac{7}{4}
    That ellipse can also be written (divide both sides by 112) \frac{x^2}{112}+ \frac{y^2}{7}= \frac{x^2}{(4\sqrt{7})^2}+ \frac{y^2}{(\sqrt{7})^2}= 1.

    That has semi-axes of length \sqrt{7} and 4\sqrt{7}. Can you calculate the coordinates of the foci from that? Then it should be easy to find the distance from that point to each point.
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