Author 
Comment/Response 
Daniele Lupo

10/09/05 12:46pm
Hi.
I've a problem in the resolution of this problem.
In the complex plane, I've a fixed circle, and a family of circles depending on parameter called g.
want to find the g value that select the circle of the family tangent to the first circle.
To solve this problem, I've imposed that the distance between centers is equal to the sum of rays, and then I've solved it to find the g parameter. Unfortunately, this seems to don't work.
In the resolution of the equation, I obtain four solutions, but noone satisfy my problem, because g must be real.
As you can see in the attached notebook, with some sample values, there's a tangent circle with g value that must be between .9 and .94. You can see it graphically. Anyway, I can't find this value as result of the equation.
Anyone can tell me where I'm wrong, and what's the correct procedure?
Thanks for your answers
Daniele
PS: I'm using Mathematica 5.1.1 on WinXP Home
Attachment: complexCircleProblem.nb, URL: , 
