Finding the equations of Conic sections

[slow_at_math]

Im having trouble finding the equations of hyberboles, ellipses, and parabolas, using only vertices and foci.
For example, two of my hw questions say

The vertices of an ellipse are (+ or - 4,0) and the foci are (+ or - 2 ,0) then find the equation and sketch teh graph. how would i go about doing this problem? i know that vertex is the opposite of the x-h and y-k thing. so the start of the equation would be x+4 or x-4 and y+4 and y-4 but i do not know what to do after that.

the other hw question is the equation of a hyberbola, vertices +- 3,0 and the foci +-4, 0.

 

[Deleted member 4993]

Im having trouble finding the equations of hyberboles, ellipses, and parabolas, using only vertices and foci.
For example, two of my hw questions say

The vertices of an ellipse are (+ or - 4,0) and the foci are (+ or - 2 ,0) then find the equation and sketch teh graph. how would i go about doing this problem? i know that vertex is the opposite of the x-h and y-k thing. so the start of the equation would be x+4 or x-4 and y+4 and y-4 but i do not know what to do after that.

the other hw question is the equation of a hyberbola, vertices +- 3,0 and the foci +-4, 0.

Go to:

http://education.yahoo.com/homework_hel ... 8_1_1_6_70

for interactive examples.