//创建抽象类abstractclassShape{publicdouble l;publicdouble L
{get{return l;}set{ l =value;}}publicdouble h;publicdouble H
{get{return h;}set{ h=value;}}publicdouble r;publicdouble R
{get{return r;}set{ r =value;}}//areapublicabstractvoidArea();staticvoidMain(string[] args){//三角形Triangle triangle =newTriangle();
triangle.Area();//圆Circle circle =newCircle();
circle.Area();}}//三角形classTriangle:Shape{publicoverridevoidArea(){double sum =0;
Console.WriteLine("请输入边长");
L =double.Parse(Console.ReadLine());
Console.WriteLine("请输入高");
H =double.Parse(Console.ReadLine());
sum =0.5* L * H;
Console.WriteLine("三角形的面积:"+ sum +"");
Console.ReadLine();}}//圆形classCircle:Shape{publicoverridevoidArea(){double sum =0;
Console.WriteLine("请输入半径");
R =double.Parse(Console.ReadLine());
sum =3.14* R * R;
Console.WriteLine("圆形的面积:"+ sum +"");
Console.ReadLine();}}