An air-traffic controller observes two airplane on his radar screen. The first is at altitude 850 meter, horizontal distance 19.8 kilometer and 24.0 degree south of west. The second airplane is at altitude 1200 meter, horizontal distance 17.3 kilometer and 22.0 degree south of west. Calculate the distance between the two airplane? (Place the x axis west, the y axis south, and the z axis vertical.)