C# Hình Chữ Nhật

using System;

using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace WindowsFormsApp3
{
    class HCN
    {
        public int cd;
        public int cr;
        public HCN(int cd,int cr)
        {
            this.cd = cd;
            this.cr = cr;
        }
        public int tinhDT()
        {
            return cd * cr;
        }
        public int tinhCV()
        {
            return (cd + cr) * 2;
        }
        public String xuatTT()
        {
            return "dt: " + tinhDT() + " cv: " + tinhCV();
             
        }
    }
}