Final answer:
A tool that can be used to identify a secure location includes a security gate, which can detect metals and indicate their height. Additionally, technology exists that can track and identify cell phones, which can also be used to remotely activate devices to gather further information.
Step-by-step explanation:
The question asks about a tool used to identify a secure location. Such a tool can be a security gate often seen at airports. The security gate has metal detection capabilities and can indicate the approximate height of detected metals above the floor. In a broader context, beyond the simple metal detection at airports, law enforcement and some criminals can identify the location of a person by utilizing technology that identifies and tracks cell phones. This technology, with the correct software, can activate a phone's microphone and camera remotely, allowing a tracking range of several thousand feet without the user's knowledge.
In cases where precise location tracking is required, another method is to use known distances between two points, such as on an athletics track, to triangulate positions. This method can be useful in wider applications, such as in law enforcement, where suspects need to be tracked within a certain area even if the exact location is unknown.