Answer:
103.4° or S76.6°E
Explanation:
The direction N43°E is perpendicular to the direction south-east when the plane turn 90° and heads in the south-east direction.
Since the distance 1/2 mile N43°E is perpendicular to the distance 1 mile south-east, we have a right angled triangle.
So, the angle θ between the aircraft's new position and old position is gotten from tanθ = 1 ÷ 1/2 = 2
θ = tan⁻¹(2) = 63.43°
So, the total angle from North to its new position is 40° + 63.43° = 103.43°
Since we need the south-east bearing, the angle from south is 180° - 103.43° = 76.57° ≅ 76.6°
So, our bearing is 103.4° or S76.6°E