b)
Program Tam_giac_can;
Uses crt;
Var a,b,c : Real;
Begin
 crlscr;
 Write('Nhap a = '); ReadIn(a);
 Write('Nhap a = '); ReadIn(b);
 Write('Nhap a = '); ReadIn(c);
 If a=b or b=c or a=c then WriteIn('Day la tam giac can')
 else
 WriteIn('Day ko phai la tam giac can')
 End.

c)
Program Tam_giac_vuong;
Uses crt;
Var a,b,c : Real;
Begin
 crlscr;
 Write('Nhap a = '); ReadIn(a);
 Write('Nhap a = '); ReadIn(b);
 Write('Nhap a = '); ReadIn(c);
  if c*c=a*a+b*b or b*b=c*c+a*a or a*a=b*b+c*c then WriteIn('Day la tam giac vuong')
 else
 WriteIn('Day ko phai la tam giac vuong')
 End.

Program Diem_Trung_binh;
Uses Crt;
Var
   Ten:String[24];
   Van,Toan,Ly,tb:Real;
Begin
   Clrscr;
   Writeln('TINH DIEM TRUNG BINH VA XEP HANG');
   Writeln('--------------------------------');
   Write('-Cho biet ho ten: ');
   Readln(Ten);
   Write('-Diem mon Van: ');
   Readln(Van);
   Write('-Diem mon Toan: ');
   Readln(Toan);
   Write('-Diem mon Ngoai ngu: ');
   Readln(Ly);
   Tb:=((Van*2)+(Toan*2)+Ngoai ngu)/5;
   If tb < 5 Then
      Begin
         Writeln('Hoc sinh: ',Ten);
         Writeln('Diem trung binh = ',Tb:4:1);
         Writeln('Xep hang: Hoc luc kem');
      End
   Else if Tb < 7 Then
      Begin
         Writeln('Hoc sinh: ',Ten);
         Writeln('Diem trung binh = ',Tb:4:1);
         Writeln('Xep hang: Hoc luc trung binh');
      End
   Else if Tb < 9 Then
      Begin
         Writeln('Hoc sinh: ',Ten);
         Writeln('Diem trung binh = ',Tb:4:1);
         Writeln('Xep hang: Hoc luc Kha');
      End
      Else
          Begin
            Writeln('Hoc sinh: ',Ten);
            Writeln('Diem trung binh = ',Tb:4:1);
            Writeln('Xep hang: Hoc luc Gioi');
         End;
   Writeln;
   Writeln(' Bam phim <Enter> de ket thuc');
   Readln;
End.