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 distance from the sending end to the point to be measured, the coordinate of the point to be measured can be uniquely determined.)