SOLUTION
Write out the sides of the given triangles
[tex]\begin{gathered} 16\operatorname{km} \\ \text{and } \\ 17\operatorname{km} \end{gathered}[/tex]To find the two possibles length of the third side, we apply the rule
[tex]\begin{gathered} \text{give two sides a,b of a triangle, the third sides will fall within the range of } \\ \text{ difference>x>sum } \\ a-b>x>a+b \end{gathered}[/tex]Applying the rule above, we have
[tex]\begin{gathered} 17-16>x>17+16 \\ 1>x>33 \end{gathered}[/tex]