a 45°-45°-90° is a triangle that can be obtained when a triangle has both of its legs with the same length
then, use the pythagorean theorem
[tex]\begin{gathered} x^2+x^2=(\sqrt[]{11})^2 \\ 2x^2=11 \\ x^2=\frac{11}{2} \\ x=\sqrt[]{\frac{11}{2}} \\ \text{rationalize} \\ x=\frac{\sqrt[]{22}}{2} \end{gathered}[/tex]
