9. What additional information do you need to prove that

Explanation
The Hypotenuse leg theorem states that if the hypotenuse and leg of a triangle are congruent to the hypotenuse and leg of another rigth triangle then the two triangles are congruent
therefore, to prove the triangles are congruent we need to know that
[tex]\begin{gathered} hypotenuse1=\text{ hypotenuse2} \\ LM=LO \end{gathered}[/tex]also, the legs must be congruent, so
[tex]OM=ON[/tex]therefore, the answer is
[tex]OM=ON[/tex]I hope this helps you