A ladder 20 feet high would be placed at what distance from the building at the bottom?

• A. 4 ft
• B. 5 ft
• C. 6 ft
• D. 8 ft

Answer: (B)

Ladder safety hinges on getting the lean angle right. A practical rule is to place the base about one-quarter of the ladder’s length away from the wall, which gives a lean of roughly 75 degrees. For a 20-foot ladder, that means about 5 feet from the building.

This 5-foot base keeps the ladder stable: the triangle formed by the wall, ground, and ladder has a vertical reach of about sqrt(20^2 − 5^2) ≈ 19.4 feet, so the ladder sits at a safe angle without tipping forward or slipping. If you set the base closer, the angle becomes very steep and the top is more likely to push inward; if you set it farther out, the angle becomes too shallow and stability decreases. The 5-foot base is the balance point for a safe, effective lean.