Final answer:
On a one-way freeway, warning triangles should be placed behind a vehicle in the event of an emergency or breakdown, starting approximately 10 feet from the rear and with additional triangles farther back at increasing intervals to alert oncoming traffic.
Step-by-step explanation:
Orange triangles, also known as warning triangles, are typically used as a roadside safety measure to alert oncoming traffic of a stationary vehicle ahead, often in the case of an emergency or breakdown. On a one-way highway such as a freeway, these triangles should be placed behind the vehicle. The first triangle should be placed approximately 10 feet from the rear of the vehicle, the second about 100 feet further back, and the third, if available, should be placed another 200 feet behind the second, all in line with the vehicle, on the shoulder of the road if possible. This progression of placement ensures that oncoming vehicles have ample warning and can move over or slow down to safely pass the stationary vehicle. Note that the placement may vary depending on the country's traffic guidelines, but the principle remains the same - to provide a gradual alert to the oncoming drivers.