c# 方法的重构

namespace shape
{
    class MyFormatHelper
    {
        /// <summary>
        /// 打印操作成功或失败消息
        /// </summary>
        public static void AlertTips(string tips)
        {
            Console.WriteLine("******************************************************");
            Console.WriteLine("* {0} *", tips);
            Console.WriteLine("******************************************************");
        }
    }

    /// <summary>
    /// 基类形状
    /// </summary>
    class shape
    {
        public const double PI=3.14;
        /// <summary>
        /// 抽象方法画图
        /// </summary>
        public virtual  void DrawShape(){}

    }
    /// <summary>
    /// 圆类，继承了形状类
    /// </summary>
    class Circle : shape
    {

        /// <summary>
        /// 覆盖了画图方法
        /// </summary>
        public override void DrawShape()
        {
            Console.WriteLine("我画了一个圆");
        }

        /// <summary>
        /// 求面积
        /// </summary>
        public  void GetArea(double r)
        {
            Console.WriteLine("圆的面积是{0}",PI * r );
        }

    }

    /// <summary>
    /// 矩形类，继承了形状类
    /// </summary>
    class Rectange : shape
    {

        /// <summary>
        /// 覆盖了画图方法
        /// </summary>
        public override void DrawShape()
        {
            Console.WriteLine("我画了一个矩形");

        }
        /// <summary>
        /// 求面积
        /// </summary>
        public  void GetArea(double lenght ,double width)
        {
            Console.WriteLine("矩形的面积是{0}", lenght * width);
        }

    }
    /// <summary>
    /// 三角形类，继承了形状类
    /// </summary>
    class Triangle : shape
    {
        /// <summary>
        /// 覆盖了画图方法
        /// </summary>
        public override void DrawShape()
        {
            Console.WriteLine("我画了一个三角形");

        }
        /// <summary>
        /// 求面积
        /// </summary>
        public void GetArea(double a, double b, double c, double s)
        {
            Console.WriteLine("三角形的面积是{0}", Math .Sqrt(s * (s - a) * (s - b) *
                     (s - c)));
        }
    }
    /// <summary>
    /// 梯形类，继承了形状类
    /// </summary>
    class Echelon : shape
    {
        /// <summary>
        /// 覆盖了画图方法
        /// </summary>
        public override void DrawShape()
        {
            Console.WriteLine("我画了一个梯形");

        }
        /// <summary>
        /// 求面积
        /// </summary>
        public void GetArea(double width, double lenght, double height)
        {
            Console.WriteLine("梯形的面积是{0}", (width + lenght) * height / 2);
        }
    }
    /// <summary>
    /// 信息类，打印画图
    /// </summary>
    class Info
    {
        public void GetInfo(params shape[] shape)
        {
            foreach (shape s in shape)
            {
                s.DrawShape();
            }
        }
    }
}
class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("请选则操作：");
            Console.WriteLine("------------------------------------------------");
            Console.WriteLine("1: 圆");
            Console.WriteLine("2: 矩形 ");
            Console.WriteLine("3: 三角形 ");
            Console.WriteLine("4: 梯形");
            Console.WriteLine("0、退出");
            int intOpCategory = 0;
            bool flag = true;

            Circle c = new Circle();
            Rectange r = new Rectange();
            Triangle t = new Triangle();
            Echelon e = new Echelon();
            Info info = new Info();
            while (flag)
            {
                try
                {
                    intOpCategory = Convert.ToInt32(Console.ReadLine());
                    switch (intOpCategory)
                    {
                        case 0:
                            flag = false;
                            break;
                        case 1:
                            info.GetInfo(c);
                            Console.WriteLine("请输入圆的半径");
                            c.GetArea(Convert.ToDouble(Console.ReadLine()));
                            break;
                        case 2:
                            info.GetInfo(r);
                            Console.WriteLine("请输入矩形的长与宽");
                            double lenght = Convert.ToDouble(Console.ReadLine());
                            double width = Convert.ToDouble(Console.ReadLine());
                            r.GetArea(lenght, width);
                            break;
                        case 3:
                            info.GetInfo(t);
                            Console.WriteLine("请分别输入输入三角形的边长");
                            double a = Convert.ToDouble(Console.ReadLine());
                            double b = Convert.ToDouble(Console.ReadLine());
                            double d = Convert.ToDouble(Console.ReadLine());
                            double s = Convert.ToDouble(Console.ReadLine());
                            t.GetArea(a, b, d, s);
                            break;
                        case 4:
                            info.GetInfo(e);
                            Console.WriteLine("请输入梯形的长宽与高");
                            double ewidth = Convert.ToDouble(Console.ReadLine());
                            double eheight = Convert.ToDouble(Console.ReadLine());
                            double elenght = Convert.ToDouble(Console.ReadLine());
                            e.GetArea(ewidth, eheight, elenght);
                            break;

                        default:
                            MyFormatHelper.AlertTips("所选操作不正确，请重新选择！");
                            break;
                    }
                }
                catch
                {
                    Console.WriteLine("输入格式不正确,请重新输入");
                }
            }

        }
    }
这是我写的类，但是我觉得是否有更好的方法来重构呢，因为每一个方法都有一个求面积的方法。我原先想过吧求面积方法写成抽象方法，传不同的参数，但是失败了，好像对于不同的参数不怎么好设计。请大家帮一下忙，帮我解决一下。先谢谢了 --------------------编程问答-------------------- 不会帮顶一下~~~~~~~~~~~~~~~~~~~

补充：.NET技术 ,  C#