Question

Two sides of a triangle have lengths 9 and 14 units. Describe what you know about the length of the third side.

Answer 1

Since we do not know anything about angles, all we can do is to give the maximum and minimum lengths of the  third side using the triangle inequality, which is:
the sum of lengths of the two shorter sides of a triangle must be GREATER than the third side (say X)

If 9 and 14 are the shorter sides, then the sum of 9 and 14 must be greather than the third side, X.  => 9+14=23>X, or X<23. .................(1)

If 14 is the longest side, then 9+third side (X) must be greater than 14, or 9+X>14, or X>14-9=5, or X>5, or 5< X ..............................(2)

Combining conditions (1) and (2)
5 < X < 23
OR
X must be greater than 5 AND X must be less than 23
OR
X must be between 5 and 23.