Path: utzoo!attcan!uunet!cs.utexas.edu!csd4.csd.uwm.edu!mrsvr.UUCP!shoreland.uucp!hallett
From: hallett@shoreland.uucp (Jeff Hallett x4-6328)
Newsgroups: comp.graphics
Subject: Re: Tangents to Three Circles
Message-ID: <890@mrsvr.UUCP>
Date: 17 Aug 89 20:04:19 GMT
References: <859@mrsvr.UUCP> 
Sender: news@mrsvr.UUCP
Reply-To: hallett@shoreland.UUCP (Jeff Hallett x4-6328)
Organization: GE Medical Systems, Milwaukee,  WI
Lines: 36

In article  beshers@cs.cs.columbia.edu (Clifford Beshers) writes:
>In article <859@mrsvr.UUCP> hallett@mrsvr.UUCP (Jeff Hallett) writes:
>
>
>   I have an interesting geometry problem.  Given three circles, I need
>   to be able to find a circle tangent to all three.  I realize that,
>   as specified, there are upto 6 possible solutions, but there is
>   always one. 
>
>Do you mean, for any 3 circles a, b and c there exists a circle d
>that is tangent to each of a, b and c?  What about the case where
>a, b and c share the same center, but each has a radius different
>from the other.  I can't visualize a circle d tangent to all three.

Gee, I'm so grateful for this solution.  Ok, so perhaps I was too
hasty in stating that there is always a solution.  I admit that I made
the assumption that there was some portion in each circle which was
disjoint from the other two.  I thereby amend the problem.

Rather than critquing the problem, how about a solution which either
finds the tangential circles or determines that there is no such
circle?


Apologies if this sounds needlessly harsh, but I find this type of
posting very insulting.  It does not help me in my predicament in the
least and only makes me feel worse for being unable to solve it in the
first place.

Thanks in advance.

--
                Jeffrey A. Hallett, PET Software Engineering
                    GE Medical Systems, W641, PO Box 414
                            Milwaukee, WI  53201
           (414) 548-5173 : EMAIL -  hallett@postron.gemed.ge.com