Answer:
[tex]\sqrt{257.77}[/tex] or 15.867 yd
Step-by-step explanation:
[tex]a^2+b^2=c^2[/tex]
[tex]9.9^2+12.4^2=x^2[/tex]
[tex]98.01+153.76=x^2[/tex]
[tex]\sqrt{257.77} =x[/tex]
15.867 = x
