Answer :

Determine the height upto which ladder reach by using trigonometry.

[tex]\begin{gathered} (14)^2=(4)^2+(l)^2 \\ 196-16=l^2 \\ l=\sqrt[]{180} \\ =13.41 \\ \approx13.4 \end{gathered}[/tex]

So answer is 13.4 feet.