按照以下要求设计接口lArea、长方形类Rectangle、正方形类Square、圆形类Circle，最终在主函数中输出长方形、正方形及圆形面积。 1.接口IArea,包含:计算面积的方法double Area(); 2.类Rectangle、类Square、类Circle继承接口，包含: ①自动属性; ②构造函数(能判断对应参数的合理性(如: x>0)); ③实现计算面积的方法Area(); 3.主函数中，创建三个对象(如下: )，分别调用方法Area(),输出三种图形的面积。IArear = new Rectangle(3, 5); //Rectangle r = new Rectangle(3, 5) Console. WriteLine("长方形的面积为: {0:0. 00) ",r. Area0); IAreas = nCw Square(3) ; Console. WriteLine(正方形的面积为: {0:0.00}，s. Area() ; IArea c = new Circle(2) ; Console. WriteLine("圆形的面积为: {0:0. 00}”，c. Area(): >输出样例: 长方形的面积为:15.00正方形的面积为:9.00圆形的面积为:12.57。使用c sharp编写

以下是代码实现：

using System;

interface IArea
{
    double Area();
}

class Rectangle : IArea
{
    private double length;
    private double width;

    public Rectangle(double l, double w)
    {
        if (l > 0 && w > 0)
        {
            length = l;
            width = w;
        }
        else
        {
            throw new ArgumentException("Length and width must be greater than 0.");
        }
    }

    public double Area()
    {
        return length * width;
    }
}

class Square : IArea
{
    private double side;

    public Square(double s)
    {
        if (s > 0)
        {
            side = s;
        }
        else
        {
            throw new ArgumentException("Side must be greater than 0.");
        }
    }

    public double Area()
    {
        return side * side;
    }
}

class Circle : IArea
{
    private double radius;

    public Circle(double r)
    {
        if (r > 0)
        {
            radius = r;
        }
        else
        {
            throw new ArgumentException("Radius must be greater than 0.");
        }
    }

    public double Area()
    {
        return Math.PI * radius * radius;
    }
}

class Program
{
    static void Main(string[] args)
    {
        IArea r = new Rectangle(3, 5);
        Console.WriteLine("长方形的面积为: {0:0.00}", r.Area());

        IArea s = new Square(3);
        Console.WriteLine("正方形的面积为: {0:0.00}", s.Area());

        IArea c = new Circle(2);
        Console.WriteLine("圆形的面积为: {0:0.00}", c.Area());
    }
}

输出结果：

长方形的面积为: 15.00
正方形的面积为: 9.00
圆形的面积为: 12.57