public StraightLineF(PointF from, PointF to) { var dirVectorF = new VectorF(from, to); var normalVectorF = dirVectorF.Rotate(Math.PI / 2.0); var unitVectorF = normalVectorF.UnitVector(); A = unitVectorF.X; B = unitVectorF.Y; C = -(A * from.X + B * from.Y); }