I need help this is 8th-grade math it is due tomorrow and the term ends on Friday

Answer:
the missing side length = 12m
Step-by-step explanation:
use the pythagorean theorem--a^2 + b^2 = c^2
a^2 + b^2 = c^2
a^2 + 5^2 = 13^2
a^2 + 25 = 169
- 25 -25
a^2 = 144 -- square each side
a = 12