First, we draw a picture
we must use pythagoras
[tex]a^2+b^2=h^2[/tex]where a and b are the sides of the triangle and h the hypotenuse
so, on this case the h is 20 because is the hypotenuse and 4 can be a or b, and the black line is the other side
then, replacing
[tex]\begin{gathered} 4^2+b^2=20^2 \\ b^2=20^2-4^2 \\ b=\sqrt[]{20^2-4^2} \\ \\ b=8\sqrt[]{6}\approx19.5959 \end{gathered}[/tex]the distance is 19.5959 feet, so the right option is second
