Question 326334: Starting from the definition of an ellipse, can you show me how you get x squared/a squared + y squared/b squared =1? Answer by Fombitz(32388) (Show Source):
You can put this solution on YOUR website! Check out the excellent derivation here.
No need to re-invent the wheel (or oval).
http://mathforum.org/library/drmath/view/52654.html