I need help!! Geometry

Answer:
I LOVE GEOMETRY!
Step-by-step explanation:
ok so for triangles A^2+B^2=C^2
a=x
b=4
c=5
4^2=16
5^2=25
25-16=9
square root of nine is 3
3,4,5 are very common pathagrum tirples, if that is how you spell it :)
Answer:
The missing side length is 3.
Step-by-step explanation:
[tex]a^{2}+b^{2} =c^{2}[/tex]