Solving Circle Equation with 2 Intersecting Vectors

[pbayer123]

Thank you for taking time to read my post, I hope I am putting into the correct area of the physics forum.

I am working with a programmer to complete a project that involves 2 intersecting vectors and a circle. The vector coordinates are known, we are trying to solve the circle equation. I have provided a visual example.

The programmer says the problem is he needs a 4th point in order to program this and is not sure how to do this. He states the following:

The equation of ellipse is:
(X -Xo)^2/A^2 + (Y-Yo)^2/B^2 = 1
where Xo,Yo - coordinates of center, A - major, B - minor semiaxes

http://curezone.com/ig/i.asp?i=69998

Thanks again.

 

[pbayer123]

Image address:
http://curezone.com/ig/i.asp?i=69998

The text is difficult to read on the image so here is what it says:

Blue squares are outputs from an algorithm

The circle can be any size
but must be in the same relationship to the AB vector (ZY = AB)

the Z point on the circle must be place on pt A

The circle must intersect any point on CB and any point on BD