C#

class Program
    {
        static void Main(string[] args)
        {
            double b;
            double h;

            Console.WriteLine("Basis: ");
            b= Convert.ToDouble(Console.ReadLine());

            Console.WriteLine("Height: ");
            h= Convert.ToDouble(Console.ReadLine());

            double area1 = Program.calcArea(b, h);
            Console.WriteLine("The area of triangle 1 is: ");
            Console.WriteLine(area1);
            Console.ReadLine();
        }

    public static double calcArea(double b, double h)
        {
            return b * h / 2;
        }
    }
}

private void panel1_MouseDown(object sender, MouseEventArgs e)
        {
            LastX = e.X;
            LastY = e.Y;
        }

        private void panel1_Paint(object sender, PaintEventArgs e)
        {
            Graphics G = panel1.CreateGraphics();
            G.DrawLine(Pens.Black, PointX, PointY, LastX, LastY);
            LastX = PointX;
            LastY = PointY;
        }

        private void panel1_MouseMove(object sender, MouseEventArgs e)
        {
            if (e.Button == MouseButtons.Left)
            {
                PointX = e.X;
                PointY = e.Y;
                panel1_Paint(this, null);