A. 

Program Dien_tich_tam_giac;
Uses Crt;
Var
   a,b,c:Integer;
   p,s:Real;
Begin
   Clrscr;
   Writeln('DIEN TICH TAM GIAC');
   Writeln('------------------');
   Write('-Nhap so thu nhat: ');
   Readln(a);
   Write('-Nhap so thu hai : ');
   Readln(b);
   Write('-Nhap so thu ba  : ');
   Readln(c);
   If (a+b>c) And (b+c>a) And (c+a>b) Then
       Begin
         Writeln('+Dung la Tam giac');
         p:=0.5*(a+b+c);
         s:=Sqrt(p*(p-a)*(p-b)*(p-c));
         Writeln('+Dien tich= ',s:10:2);
      End
   Else
       Writeln('+Khong phai la Tam giac');
   Writeln;
   Writeln('   Bam phim <Enter> de ket thuc');
   Readln;
End.

B.

Program Chu_Nhat_Program;
Uses Crt;
Var a,b,s: real;
Begin
Clrscr;
Writeln(‘ TINH DIEN TICH HINH CHU NHAT:’);
Write(‘Nhap chieu dai=’); readln(a);
Write(‘Nhap chieu r />s:=a*b;
Writeln(‘Dien tich hinh chu nhat la:’,s:6:2);  Readln;

End.

Bài A:

Program BTT;
Uses crt;
Var s,a,h: longint;
Begin
        Clrscr;
        Write('Nhap chieu dai day: '); Readln(a);
        Write('Nhap chieu cao: '); Readln(h);
        s:=a*h/2;
        Write('Dien tich la: ',s:0:2);
        Readln
End.

Bài B:

Program BTT;
Uses crt;
Var s,a,b: longint;
Begin
        Clrscr;
        Write('Nhap chieu dai: '); Readln(a);
        Write('Nhap chieu rong: '); Readln(b);
        s:=a*b;
        Write('Dien tich la: ',s:0:2);
        Readln
End.