Anybody Know This. ?

Answer:
About 16.7
Step-by-step explanation:
[tex]a^{2} +b^{2} =c^{2} \\9^{2}+b^{2} =19^{2} \\19^{2}-9^{2}=b^{2}\\361-81=b^{2}\\280=b^{2}\\\sqrt{280} =16.7332005307\\[/tex]
rounded to the nearest tenth:
16.7
(Please let me know if I was right and if I helped!)