Title: How to Determine the incenter of a 2D triangle
procedure Incenter(x1, y1, x2, y2, x3, y3: Double; var Px, Py: Double);
var
Perim: Double;
Side12: Double;
Side23: Double;
Side31: Double;
begin
Side12 := Distance(x1, y1, x2, y2);
Side23 := Distance(x2, y2, x3, y3);
Side31 := Distance(x3, y3, x1, y1);
{ using Heron's S=UR }
Perim := 1 / (Side12 + Side23 + Side31);
Px := (Side23 * x1 + Side31 * x2 + Side12 * x3) * Perim;
Py := (Side23 * y1 + Side31 * y2 + Side12 * y3) * Perim;
end;
(* End Of Incenter*)