What is the correct angle for non-self-supporting ladders to maintain safety?

The correct angle for non-self-supporting ladders is ideally set as the ratio of the base distance from the wall to the height it reaches. The angle is commonly expressed using the 4-to-1 rule, which suggests that for every four feet of height, the base of the ladder should be one foot away from the wall. Therefore, using the working length of the ladder, this means that the ladder should be positioned at approximately a quarter of its working length from the base to ensure it is stable and secure. This angle provides optimal support and helps prevent the ladder from slipping or falling, thus maintaining safety during use.

It is important to note that the other options do not align with the established safety guidelines for ladder use. For instance, suggesting an angle based on a greater ratio may lead to increased risk of toppling or loss of balance, while a lesser ratio could result in the ladder being too steep, similarly compromising safety. The quarter rule is a practical application of angle positioning that has been adopted for effective ladder safety.