The above drawing describes the situation.
By definition
[tex]\cos (angle)=\frac{\text{ adjacent side}}{\text{ hypotenuse}}[/tex]From the picture
[tex]\begin{gathered} \cos (25^o)=\frac{19}{x} \\ \cos (25^o)\cdot x=19 \\ x=\frac{19}{\cos (25^o)} \\ x=21\text{ ft} \end{gathered}[/tex]
