室内三点定位。三边定位算法，一种基于距离信息实施定位的方法。已知三个发送端点的坐标和发送端到待测点间的距离，就可以唯一确定待测点坐标。(Indoor three point location. Three edge location algorithm, a method based on distance information for positioning. Given the coordinates of the three sending endpoints and the dista