(Middle school math) please help, thank you

Answer:
18.68 inches
Step-by-step explanation:
slant height² = r² + h²
slant height = [tex]\sqrt{r^{2} + h^{2} }[/tex]
sh = [tex]\sqrt{5^{2} + 18^{2} }[/tex]
sh = [tex]\sqrt{25 + 324}[/tex]
sh = [tex]\sqrt{349}[/tex]
sh = 18.68154 inches