Масштабирование графика

    double masX = e.Width / aa;
    double masY = e.Heigh / aa;
 
    double Scale = Math.Max(masX, masY);
 
    double size = 0.15;
 
    for (double fi = A; fi < B; fi += k)
        {
            
            double xp = aa * Math.Cos(2 * fi) ;
            double yp = aa * Math.Cos(2 * fi) * Math.Sin(fi) / Math.Cos(fi) ;
 
            xp = aa * Math.Cos(2 * (fi + k));
            yp = aa * Math.Cos(2 * (fi + k)) * Math.Sin(fi + k) / Math.Cos(fi + k);
         
            
            e.Surface.DrawLine(0xFFFF00, x1 * Scale * size, y1 * Scale * size, x2 * Scale * size, y2 * Scale * size);
 
        }

private void DrawLine(Point p1, Point p2, Brush color)
{
      Canv.Children.Add(new Line()
      {
          X1 = coeffs.kX * p1.X + coeffs.DispX,
          X2 = coeffs.kX * p2.X + coeffs.DispX,
          Y1 = GraphGrid.ActualHeight - (coeffs.kY * p1.Y + coeffs.DispY),
          Y2 = GraphGrid.ActualHeight - (coeffs.kY * p2.Y + coeffs.DispY),
          Stroke = color
      });
 }

public class Coeffs
{
    public double kX { get; private set; }
    public double kY { get; private set; }
    public double DispX { get; private set; }
    public double DispY { get; private set; }
 
    public Coeffs(GraphArea area, double Width, double Height)
    {
        kX = Width / (area.MaxX - area.MinX);
        kY = Height / (area.MaxY - area.MinY);
 
        DispX = -area.MinX * kX;
        DispY = -area.MinY * kY;
    }
}

private void Canv_SizeChanged(object sender, SizeChangedEventArgs e)
{
    if (GraphGrid.ActualHeight == 0 || GraphGrid.ActualWidth == 0)
        return;
 
    ReDraw();
}