Gandalf the Grey started in the Forest of Mirkwood at a point with coordinates (1, -3) and arrived in the Iron Hills at the point with coordinates (2, 1). If he began walking in the direction of the vector and changes direction only once, when he turns at a right angle, what are the coordinates of the point where he makes the turn.

Question

Gandalf the Grey started in the Forest of Mirkwood at a point with coordinates (1, -3) and arrived in the Iron Hills at the point with coordinates (2, 1). If he began walking in the direction of the vector  and changes direction only once, when he turns at a right angle, what are the coordinates of the point where he makes the turn.

anonymous · Answer

This problem statement is ambiguous. What does this mean:
  "If he began walking in the direction of the vector"