Bài 1:

unit toan;

interface

         function dtht(x,y,h:integer):real;

         function sht(r:integer):real;

         function uscln(x,y:integer):integer;

         function ktnt(x:integer):boolean;

         function fibo(n:integer):integer;

implementation

              function dtht(x,y,h:integer):real;

                   dtht:=((x+y)*h)/2;

              end;

              function sht(r:integer):real;

                   sht:= pi*r*r;

              end;

              function uscln(x,y:integer):integer;

                   while x<>y do

                   if x> y then x:=x-y

                   else y:=y-x;

                   uscln:=x;

              end;

              function ktnt(x:integer):boolean;

              var i:integer;

                   ktnt:=false;

                   for i:=2 to x-1 do

                       if x mod i=0 then exit;

                   ktnt:=x>1;

              end;

              function fibo(n:integer):integer;

                   if n<3 then fibo:=1

                   else fibo:=fibo(n-2)+fibo(n-1);

              end;

end.

program sd_toan;

uses toan;

var i:integer;

     writeln(uscln(9,3));

     writeln(dtht(2,3,4):0:0);

     writeln(sht(2):0:0);

     if ktnt(5)=true then writeln('la so nt')

     else writeln('ko la so nt');

     write('day fibo:');

     for i:=1 to 8 do

         write(fibo(i):3);

     readln;

end.