Final answer:
The second aircraft should turn 90° and fly due north to return directly to its base after flying 10 miles due east and then due south, consistent with the symmetry to the flight path of the first airplane which turned and returned to base after its own maneuvers.
Step-by-step explanation:
The subject of this question is Mathematics, and it involves geometry and the principles of displacement. The question describes the different flight paths of two airplanes and asks what the second aircraft should do to return to its starting point. Given that one airplane flies 10 miles due south from its base, turns 90° and flies due west before returning directly to base, the second aircraft's movements should be symmetrical to the first, but in the perpendicular directions. As such, after flying 10 miles due east and turning 90° to fly due south, to return directly to its original starting point, the second aircraft should turn 90° and fly due north.