I’m so confused I need help please!!

Answer:
5. 9 8. [tex]2\sqrt{10}[/tex]
Step-by-step explanation:
a²+b²=c²
so for #5 12²+b²=15²
144+b²=225 (subtract 144 from both sides)
b²=81
b=9
For #8
9²+b²=11²
81+b²=121 (subtract 81 from both sides)
b²=40
b=[tex]\sqrt{40}[/tex]
[tex]\sqrt{40}[/tex]=
[tex]2\sqrt{10}[/tex]