public String isTriangle(){
	   if (checkTriangle() &&( a == b || b == c || c == a)){
		  return "Tam giac can";
	   		
	   }
	   else if (checkTriangle() &&( a*a == (b*b + c*c) || (b*b == (c*c + a*a)) || (c*c == (a*a + b*b))))
		   return "Tam giac vuong";
	   else 
		   return "Tam giac thuong";
   }