Answer
20.6 ft
Work Step by Step
We are given the equation:
$\sqrt{( (x)^{2} + (4x)^{2} )}$
It is said that the ladder is 5 feet away from the wall; thus, x=5, and we plug it into the equation:
=$\sqrt{( (x)^{2} + (4x)^{2} )}$
=$\sqrt{( (5)^{2} + (4(5))^{2} )}$
=$\sqrt{(425)}$
=20.6 ft