Two sides of a triangle are 13 and 30. what is the lower boundary for the length of the 3rd side

30+13+x=180
43+x=180
x=137

The third side is 137

If you’re talking about the side lengths then the third side is either a number less than 43 OR a number less than 17
The 43 is if it’s the hypotenuse and the 17 is if it’s one of the other sides

If you’re talking about angles, then all of the angles should equal 180 degrees so 30 + 13 = 43 . 180 - 43 = 137 degrees