minimum distance of 2 ships, a navy one and an enemy one
Source: Vietnamese MO (VMO) 1965
August 22, 2018
geometryminimum
Problem Statement
At a time , a navy ship is at a point , while an enemy ship is at a point cruising with speed perpendicular to . The speed and direction of the enemy ship do not change. The strategy of the navy ship is to travel with constant speed at a angle to the line .
1) Let be chosen. What is the minimum distance between the two ships? Under what conditions will the distance vanish?
2) If the distance does not vanish, what is the choice of to minimize the distance? What are directions of the two ships when their distance is minimum?