Finding the ellipse equation from a vector and two foci

  • Thread starter Thread starter Lurid
  • Start date Start date
  • Tags Tags
    Conics Ellipse
Join the discussion
Registration is free. Ask a follow-up in this thread, or start your own.
1 reply · 2K views
Lurid
Messages
14
Reaction score
0

Homework Statement


Given the vector (6,-15) and foci (6,10) (6,-14),
Find the equation of the conic.

Homework Equations



Vector = <6,-15>
(x-h)2/a2 + (y-k)2/b2 = 1

Foci (h+c,k) and (h-c,k)
vertices (h+a,k), (h-a,k)

The Attempt at a Solution


k = 6
h=-2
a=-12
I'm not sure what I'm doing. How do I know that this conic is an ellipse, and not a hyperbola? And how do I find b and c, after finding a?

edit:
How does a vector even relate to the equation of an ellipse?
 
Last edited:
Physics news on Phys.org
I assume the point (6, -15) is a point on the ellipse.

The expressions you've written down for the locations of the foci are for when the foci lie on the same horizontal line. In this case, the foci lie on the same vertical line.

Your value for a is wrong.