find circle to circle intersection 
circle 0 at (-0.100000,-0.200000) with radius 2.000000 
circle 1 at (2.000000,1.000000) with radius 2.100000 
distance d between centers 2.418677 
distance a (x0,y0) to (x2,y2) 1.124582 
point (x2,y2) on line between centers (0.876410,0.357949) 
distance h from intersection to a on (x2,y2) 1.653879 
try (x3p,y3p) (1.696964,1.793918) err=6.892652e+00 
 a solution, intersection (x3,y3) is (1.696964,-1.078021) 
 a solution, intersection (x3,y3) is (0.055856,1.793918) 
try (x3m,y3m) (0.055856,-1.078021) err=6.892652e+00