\psset{linewidth=2\pslinewidth}
\pstGeonode[PosAngle={0,-135,90},PointSymbol={*,*,square}](1,0){A}(-2,-1){B}(0,1){C}
\pstCircleOA[linecolor=red]{A}{B}
\pstCircleOA[linecolor=green, DistCoef=2 3 div, Radius=\pstDistAB{A}{C}]{A}{}
\pstCircleOA[linecolor=blue, Radius=\pstDistAB{B}{C}]{A}{}
\pstCircleOA[linecolor=magenta, Radius=\pstDistAB{A}{C}]{B}{}
\pstCircleOA[linecolor=cyan, Diameter=\pstDistAB{A}{C}]{B}{}
\pstCircleAB[linecolor=yellow]{B}{C} 