1. The problem asks to find the diagonal of a rectangle with width 2 feet and length 4 feet. 2. Recall that the diagonal $d$ of a rectangle can be found using the Pythagorean theorem: $$d=\sqrt{w^2 + l^2}$$ where $w$ is width and $l$ is length. 3. Substitute the given values: $$d=\sqrt{2^2 + 4^2}$$ 4. Calculate the squares: $$d=\sqrt{4 + 16}$$ 5. Sum the values inside the square root: $$d=\sqrt{20}$$ 6. Simplify the square root if possible: $$d=2\sqrt{5}$$ feet. 7. Therefore, the diagonal of the rectangle is $2\sqrt{5}$ feet, which approximately equals $$2\sqrt{5} \approx 4.47$$ feet.