MathDB
Problem 2, Olympic Revenge 2010

Source: IX Olympic Revenge - 2010

January 28, 2013
geometryreal analysisreal analysis unsolved

Problem Statement

Joaquim, José and João participate of the worship of triangle ABCABC. It is well known that ABCABC is a random triangle, nothing special. According to the dogmas of the worship, when they form a triangle which is similar to ABCABC, they will get immortal. Nevertheless, there is a condition: each person must represent a vertice of the triangle. In this case, Joaquim will represent vertice AA, José vertice BB and João will represent vertice CC. Thus, they must form a triangle which is similar to ABCABC, in this order.
Suppose all three points are in the Euclidean Plane. Once they are very excited to become immortal, they act in the following way: in each instant tt, Joaquim, for example, will move with constant velocity vv to the point in the same semi-plan determined by the line which connects the other two points, and which would create a triangle similar to ABCABC in the desired order. The other participants act in the same way. If the velocity of all of them is same, and if they initially have a finite, but sufficiently large life, determine if they can get immortal.
Observation: Initially, Joaquim, José and João do not represent three collinear points in the plane