Answer: The distance of the shortest route of return is 400
Explanation:
The direction of travel of the plane forms a right angle triangle ABC as shown in the attached photo. C represents the starting point of the plane. To determine the distance of the shortest by which the plane can return to its starting point, BC, we would apply the Pythagorean theorem which is expressed as
Hypotenuse² = opposite side² + adjacent side²
BC² = 320² + 240²
BC² = 160000
BC = √160000
BC = 400