Originally Posted by bendsley

It is not against the law for a cop to be out of sight for them to radar you. The state posts the fastest speed limit you should drive, and you should not go over that speed. Whether or not a cop is in plain sight or not is irrelevant. You should not go over the posted speed whether you can see them or not.

The speed limit sign is there because of the law. I wouldn't expect a state to post a sign and me not automatically think it was radar enforced.