NavList:

My posts on the subject: 

 https://navlist.net/m2.aspx/Finding-Symmedian-LaPook-dec-2010-g14901

https://navlist.net/m2.aspx/Finding-Symmedian-LaPook-dec-2010-g14916 

https://navlist.net/m2.aspx/Finding-Symmedian-LaPook-dec-2010-g14926

https://navlist.net/m2.aspx/Finding-Symmedian-LaPook-dec-2010-g14970

https://navlist.net/m2.aspx/Finding-Symmedian-LaPook-dec-2010-g15006

https://navlist.net/m2.aspx/Finding-Symmedian-LaPook-dec-2010-g15007

https://navlist.net/m2.aspx/Cocked-hats-symmedian-points-LaPook-dec-2010-g15014

https://navlist.net/m2.aspx/That-darned-old-cocked-hat-LaPook-dec-2010-g14723

https://navlist.net/m2.aspx/That-darned-old-cocked-hat-LaPook-dec-2010-g14770

https://navlist.net/m2.aspx/That-darned-old-cocked-hat-LaPook-dec-2010-g14725

https://navlist.net/m2.aspx/old-cocked-hat-synthesis-LaPook-dec-2010-g14919

https://navlist.net/m2.aspx/simple-threebody-fix-puzzle-LaPook-dec-2010-g14925

https://navlist.net/m2.aspx/Determining-center-cocked-hat-LaPook-nov-2010-g14368

https://navlist.net/m2.aspx/Finding-Symmedian-LaPook-dec-2010-g15007

And there is an easy way to plot the  symmedian point:

https://navlist.net/m2.aspx/Symmedian-point-plotters-for-saleFifty-dollars-each-LaPook-jan-2011-g15347

https://navlist.net/m2.aspx/Symmedian-point-plotters-for-saleFifty-dollars-each-LaPook-jan-2011-g15382

https://navlist.net/m2.aspx/Symmedian-point-plotters-for-saleFifty-dollars-each-LaPook-jan-2011-g15391

We have discussed all of this thouroughly in December 2010:

http://www.navlist.net/sort2.aspx?y=201012&sort=su&y2=201012&author=&subject=

gl