Re: Fast help for circle problem

*To*: mathgroup at smc.vnet.net*Subject*: [mg13327] Re: [mg13261] Fast help for circle problem*From*: MJE <evans.nospam at gte.net>*Date*: Mon, 20 Jul 1998 02:49:49 -0400*Organization*: None*References*: <199807170717.DAA06619@smc.vnet.net.>*Sender*: owner-wri-mathgroup at wolfram.com

Funny thing -- a fellow engineer asked me this same type of question a few months ago. This is a classic four-bar linkage problem. Look up the answer in a dynamics textbook. The four bars are joined at the centers of the circles. Regards, Mark E. jmittag wrote: > > We are looking for a solution for the following problem: > > Given are 3 circles, each with center coordinates and radius. Circle 1 > is touching circle 2 and circle 2 is touching circle 3 (without any > intersection). As a special case circle 1 is also touching circle 3. > > We are looking for circle 4, which is touching circles 1 to 3. > > The equation for one circle "i" is as follows: > > (ri+r4)^2=(x4-xi)^2+(y4-yi)^2 with i = 1,2,3 > > We need a symbolic solution for x4, y4 and r4. > > Thanks in advance! > > Jens Mittag > > email: Jens.Mittag at tu-berlin.de

**References**:**Fast help for circle problem***From:*jmittag <jmittag@b7-01.bv.TU-Berlin.DE>