The sides of an isosceles triangle are 3 and 7. The circumference of the triangle is______ .

The sides of an isosceles triangle are 3 and 7. The circumference of the triangle is______ .


(1) If 3 is the waist length and 7 is the base length, the triangle does not exist because 3 + 3 < 7; (2) if 7 is the waist length, the sum of the two sides of the triangle is greater than the third side. Therefore, the perimeter of the triangle is 7 + 7 + 3 = 17