public void LinePerpendicularToLineTest()
{
Point3d p1 = new Point3d(1, -5, -1);
Vector3d v1 = new Vector3d(-2, 3, 4);
Line3d l1 = new Line3d(p1, v1);
Point3d p2 = new Point3d(-2, 1, 2);
Vector3d v2 = new Vector3d(-2, 2, 3);
Line3d l2 = new Line3d(p2, v2);
Assert.IsTrue(l1.PerpendicularTo(l2) == new Point3d(-4, 3, 5));
}
