A blind-spot detection system includes an angle-detector, a radar-sensor, and a controller. The angle-sensor is used to determine a trailer-angle relative to a host-vehicle of a trailer being towed by the host-vehicle. The radar-sensor is used to detect an other-vehicle present in a blind-zone proximate to the host-vehicle. The controller is in communication with the angle-detector and the radar-sensor. The controller is configured to adjust a sensing-boundary that defines the blind-zone based on the trailer-angle.