progam ban_tu_chon;

uses crt;

var a,b,c :real;

BEGIN

clrscr;

    write('nhap canh a thu nhat'); Read(a);

    write('nhap canh b thu hai:'); Readln(b);

    write('nhap canh c thu ba'); Readln(c);

if (a>=b+c) or (b>=c+a) or (c>=a+b) then write('ba canh tren khong phai cua mot tam giac')

else

if (a=b) or (b=c) or (c=a) then write('tam giac tren la tam giac can');

else

if a=b=c then write('tam giac tren la tam giac deu')

else

if (a*a=b*b+c*c) or (b*b=c*c+a*a) or (c*c=a*a+b*b) then write('tam giac tren la tam giac vuong');

readln;

END.

Xin hay nhất

ví dụ  ba số a, b, c bất kỳ

ta có:

uses crt;
var a,b,c:real;
begin
   clrscr;
   write('Nhap a: '); readln(a);
   write ('Nhap b: '); readln(b);
   write('Nhap c: '); readln(c);
   if ((a+b)>c) and ((b+c)>a) and ((a+c)>b) then
   writeln(a:4:2,',',b:4:2,',',c:4:2, ' la ba canh cua tam giac')
   else
   writeln(a:4:2,',',b:4:2,',',c:4:2, ' khong phai la ba canh cua tam giac');
   readln
end.