>>684
試した
Point pa=new Point(0,0),pb=new Point(1,0);
Vector v = Vector.Subtract(pa,pb);
Console.WriteLine("{0},{1},{2},{3}",pa,pb,v,Vector.ToDegrees(v.Direction));
pb=new Point(0,1);
v = Vector.Subtract(pa,pb);
Console.WriteLine("{0},{1},{2},{3}",pa,pb,v,Vector.ToDegrees(v.Direction));
結果
{X=0,Y=0},{X=1,Y=0},{1, 0, mag=1},0
{X=0,Y=0},{X=0,Y=1},{0, 1, mag=1},90
0度は右で無いっすか?