The bottom of a ladder is to be placed out from the wall ____ the length of the vertical distance from the top of the ladder's support to its base.

• A. 1/2
• B. 1/8
• C. 1/4
• D. 1/3

Answer: (C)

When leaning a ladder, the distance its base sits from the wall should be enough to create a safe, roughly seventy-five degree angle. The standard rule is to place the bottom a distance from the wall equal to about one quarter of the ladder’s height against the wall. This one-quarter rule keeps the ladder stable: if it’s too steep, the top can tip forward; if it’s too shallow, the base can slip. In mathematical terms, with height h and base b, tan(angle) = h/b; using b = h/4 gives tan(angle) = 4, which corresponds to about seventy-five degrees. For example, if the ladder reaches eight feet up the wall, the base should be about two feet out. This is why the correct choice is one quarter of the height.