Find the length of the missing side. Leave your answer in simplest radical form.

Answer:
[tex]\sqrt{69}[/tex]
Step-by-step explanation:
from the pythagorean theorem:
[tex]a^2 + b^2 = c^2\\10^2 + b^2 = 13^2\\100 + b^2 = 169\\b^2 = 69\\b = \sqrt{69}[/tex]