Micha is an IT engineer and is adding a Wi-Fi range extender to an office. His Wi-Fi router base is located in a hallway, and he needs to know how far away the extender is, but he cannot measure directly because a wall is in his way. Using the Pythagorean theorem, he measures straight down the hall toward the door, which is 4 meters. He then turns 90° and measures through the doorway 4 meters to the extender. How far away is the extender from the router base, rounded to the nearest tenth?