please help ahh I don’t understand

Answer:
b. 37
Step-by-step explanation:
Use Pythagorean theorem [tex]a^2+ b^2= c^2[/tex]
a=12in
b=35in
c=? (Spine)
[tex]a^2+ b^2= c^2[/tex]
[tex]12^2+35^2=c^2[/tex]
[tex]144+1225=c^2[/tex]
[tex]1369=c^2[/tex]
[tex]\sqrt{1369} =c[/tex]
[tex]37=c[/tex]
The spine is 37 in