We use pythagoras theorem
[tex]\text{hypothenus}^2=opposite^2+adjacent^2[/tex]Let y represent the other leg
[tex]\begin{gathered} 20^2=11^2+y^2 \\ 400=121+y^2 \\ y^2=400-121 \\ y^2=279 \\ y=\sqrt[]{279} \\ y=3\sqrt[]{31}\text{ cm} \\ y=16.70\text{ cm} \\ \end{gathered}[/tex]The measure of the other leg is 16.70 cm