The given sides are 11 and 7.
So from the pythagoras theorem, when we take the unknown as base or altitude.
[tex]\begin{gathered} 11^2=7^2+x^2 \\ 121=49+x^2 \\ 72=x^2 \\ x=8.45 \end{gathered}[/tex]When the unknown is hypotenuse,
[tex]\begin{gathered} x^2=121+49=170 \\ x=\sqrt[]{170}=13.03 \end{gathered}[/tex]So the range of x is,
[tex]8.45\leq x\leq13.03[/tex]