Answer: 5, 6, 7, 8, 9, or the numbers 5-9 inclusive.
Step-by-step explanation: The Triangle Inequality Conjecture states that any two sides of a triangle added up will be larger than the third. To easily prove this, you can add the two smaller sides to see if it is bigger than the larger side. Using this conjecture, we can calculate that 5 works, 6 works, 7 works, 8 works (8 is larger than 7 so now we do 3+7), and 9 works.