In the figure shown below, � C is on the segment with endpoints � A and � D . The distance between � A and � B is 2 , 0 0 0 2,000 km, between � A and � C is 1 , 6 0 0 1,600 km, between � A and � D is 2 , 5 0 0 2,500 km, and between � B and � C is 1 , 2 0 0 1,200 km. What is the distance, in kilometers, between � B and � D ?