using System;

​

// Nhap vo 3 diem A B O => Xuat ra C D DienTich, CHU_VI HBH ABCD OXY

​

/*

    Nhap vo 3 diem A B O => (xA, yA) => class Diem => { double x, double y }

    void NhapDiem()

    {

        while(true)

        {

            try

            {

                Console.WriteLine("x = ");

                x = Convert.ToDouble( Console.ReadLine() );

                Console.WriteLine("y = ");

                y = Convert.ToDouble( Console.ReadLine() );

            }

            catch(FormatException e)

            {

                // chui no

                continue;

            }

        }

    }

        => viet ham nhap => nhap ABO (...) ABO ko trung nhau khi 

                                    X1 = X2 ^ Y1 = Y2 => Dinh Nghia toan tu == trung lop Diem => public static operator ==(Diem diem1, Diem diem2)

                                                                                              => public static operator !=(Diem diem1, Diem diem2)

    -----------------------------------------

    class HBH => private Diem diemA, diemB, diemC ...    ABCDO

    void NhapThongTinHinhBinhHanh()

    {

        Console.WriteLine("Nhap vo diem A: ");

        diemA.NhapDiem();

        Nhap vo diem A: 

        x = 5

        y = 6

        do

            Nhap vo diem B: 

            x = 5

            y = 6

        while ( diemA == diemB );

        do

            Nhap vo diem O: 

            x = 5

            y = 6

        while ( diemO == diemA || diemO == diemB ); 

        that ra con kiem tra diem no co thang hang ko nhung de bai ko keu

        O la trung diem cua AC, BD => 

        O la trung diem cua AC => xO = ( xA + xC ) / 2 => ra dc C D 

        diemC.X = ...

        diemC.Y = ...

        ...

        ...

    }

    CHU_VI: AB + AC + CD + DA = 2AB + 2 AC = 2 * (AB + AC) => double TinhChuVi ()

    => | AB | = Math.Sqrt(Math.Pow((X.SAU - X.DAU), 2 ) + Math.Pow((Y.SAU - Y.DAU), 2 )) => double TinhKhoangCach2Diem(Diem diemDau, Diem diemCuoi)

    double TinhDienTich() 

    {

        double AB = TinhKhoangCach2Diem( diemA, diemB )

        double AC = TinhKhoangCach2Diem( diemA, diemC )

        double BC = TinhKhoangCach2Diem( diemB, diemC )

        double NuaCHuVi = ( ... )

        double DienTichTamGiacABC = Math.Sqrt( ... );

        return 2 * DienTichTamGiacABC;

    }

    double XuatKetQua() Console.WriteLine( ... )

    class Program

    {

        HinhBinhHanh hinhBinhHanhABCD = new HinhBinhHanh();

        hinhBinhHanhABCD.Nhap...

        hinhBinhHanhABCD.Xuat...

    }

*/

class Diem

{

    private double x;

    private double y;

    public double X

    {

        get { return x; }

        set { x = value; }

    }

    public double Y

    {

        get { return y; }

        set { y = value; }

    }

    public void NhapDiem()

    {

        Console.Write("Nhap x : ");

        x = Convert.ToDouble(Console.ReadLine());

        Console.Write("Nhap y : ");

        y = Convert.ToDouble(Console.ReadLine());

    }

    public static bool operator == (Diem Diem1, Diem Diem2)

    {

        return (Diem1.x == Diem2.x && Diem1.y == Diem2.y);

    }

    public static bool operator != (Diem Diem1, Diem Diem2)

    {

        return !(Diem1.x == Diem2.x && Diem1.y == Diem2.y);

    }

}

​

class HinhBinhHanh

{

    private Diem DiemA;

    private Diem DiemB;

    private Diem DiemC;

    private Diem DiemD;

    private Diem DiemO;

    public void Nhap()

    {

        Console.WriteLine("Nhap Diem A :");

        DiemA = new Diem();

        DiemA.NhapDiem();

        do

        {

            Console.WriteLine("Nhap Diem B :");

            DiemB = new Diem();

            DiemB.NhapDiem();

        }

        while(DiemA==DiemB);

        do

        {

            Console.WriteLine("Nhap Diem O :");

            DiemO = new Diem();

            DiemO.NhapDiem();

        }

        while((DiemA==DiemO) || (DiemB==DiemO));

        DiemC = new Diem();

        DiemD = new Diem();

        DiemC.X = 2 * DiemO.X  - DiemA.X;

        DiemC.Y = 2 * DiemO.Y  - DiemA.Y;

        DiemD.X = 2 * DiemO.X  - DiemB.X;

        DiemD.Y = 2 * DiemO.Y  - DiemB.Y;

    }

    public double TinhDoDai(Diem DiemSau, Diem DiemDau)

    {

        return Math.Sqrt( Math.Pow( DiemSau.X - DiemDau.X, 2 ) + Math.Pow( DiemSau.Y - DiemDau.Y, 2 ) )  ;

    }

    public double TinhDienTich()

    {

        double AB =  TinhDoDai( DiemA, DiemB );

        double AC =  TinhDoDai( DiemA, DiemC );

        double BC =  TinhDoDai( DiemC, DiemB );

        double NuaChuVi = ( AB + AC + BC) / 2;

        return 2 * Math.Sqrt( NuaChuVi * ( NuaChuVi - AB ) * ( NuaChuVi - AC ) * ( NuaChuVi - BC ) );

    }

    public double TinhChuVi()

    {

        double AB =  TinhDoDai( DiemA, DiemB );

        double AC =  TinhDoDai( DiemA, DiemC );

        return 2 * ( AB + AC );

    }

    public void XuatKetQua()

    {

        Console.WriteLine("Dien Tich HBH la : {0}", TinhDienTich());

        Console.WriteLine("Chu Vi HBH la : {0}",TinhChuVi());

    }

}

​

​

public class Program

{

    public static void Main()

    {

        HinhBinhHanh HinhBinhHanhABCD = new HinhBinhHanh();

        HinhBinhHanhABCD.Nhap();

        HinhBinhHanhABCD.XuatKetQua();

    }

}