Finding the equation of an ellipse

[js14]

find the equation of an ellipse whose foci is (0,4)?

Im not really sure of how to begin with this. Its actually a graph problem and it only gives the foci. can someone help me with this?

 

[eumyang]

find the equation of an ellipse whose foci is (0,4)?

Im not really sure of how to begin with this. Its actually a graph problem and it only gives the foci. can someone help me with this?

Foci are two points, and you only gave one. We also need one of the following to be able to find the equation:
- length of the major axis
- value of a
- coordinates of the vertices
- length of the minor axis
- value of b
- endpoints of the minor axis
- eccentricity of the ellipse
(I think that covers it)

Without any of the above, we can't find the equation. You mention that this is a graph problem, so if you have the graph with the coordinate axes labeled, you should be able to get the values of a and b. Can you upload the picture of the graph?

 

[js14]

Its alright I figured it out. Thanks for replying though!

 

[HallsofIvy]

What, exactly, did you figure out? There exist an infinite number of ellipses having one focus at (0, 4).