Final answer:
The reflective orange triangle on the back of a vehicle signifies that the vehicle is slow-moving. It uses a corner reflector to reflect light back to its source, thereby increasing visibility and safety.
Step-by-step explanation:
The reflective orange triangle on the back of a vehicle is a warning sign indicating that the vehicle is a slow-moving one, often traveling at 25 miles per hour or less. This sign is a type of corner reflector, which is an object consisting of two mutually perpendicular reflecting surfaces that cause light, such as from headlights on your car, to be reflected back exactly parallel to the direction from which it came. The orange triangle, therefore, serves as a safety mechanism, especially during times of low visibility, by alerting other drivers to the presence of a slow-moving vehicle and to proceed with caution.