[Az-Geocaching] Find the center

I need a little help from some caching experts out there. I want to
find the center of 3 sets of coordinates and can not see the forest for
the trees here. It should be easy I think. For instance: Point 1 is
N34 36.346 W112 29.115, Point 2 is N34 36.652 W112 27.942, Point 3 is
N34 36.224 W112 28.532 I am looking for the coordinates at the dead
center of these 3 points.

Also, does anyone remember if there is a suggestion as to how far apart
caches need to be??

Thank you in advance, Bob Smith, Team Petite Elite