Answer:
8.31
Step-by-step explanation:
Using the Pythagorean Theorem:
[tex]a^2+b^2=c^2[/tex]
[tex]10^2+b^2=13^2[/tex]
[tex]100+b^2=169[/tex]
[tex]b^2=69[/tex]
[tex]b = \sqrt{69}[/tex]
[tex]b = 8.306623863[/tex]
The side length for [tex]x[/tex], rounded to the nearest hundredths, would be 8.31.