An air-traffic controller observes two aircraft on his radar screen. The first is at altitude 750 m, horizontal distance 20.0 km, and 25.0° south of west. The second aircraft is at altitude 1050 m, horizontal distance 17.0 km, and 17.0° west of south.

Question

An air-traffic controller observes two aircraft on his radar screen. The first is at altitude 750 m, horizontal distance 20.0 km, and 25.0° south of west. The second aircraft is at altitude 1050 m, horizontal distance 17.0 km, and 17.0° west of south. 
(a) Write the displacement vector FROM the first plane TO the second plane, letting i represent east, j north, and k up.
  
  i? 
  j? 
  k?

(b) How far apart are the two planes?