UFO can catch the turtle for any inital position
Source: IMO LongList 1970 - P55
May 24, 2011
trigonometrycombinatorics unsolvedcombinatorics
Problem Statement
A turtle runs away from an UFO with a speed of . The UFO flies meters above the ground, with a speed of . The UFO's path is a broken line, where after flying in a straight path of length (in meters) it may turn through for any acute angle such that . When the UFO's center approaches within meters of the turtle, it catches the turtle. Prove that for any initial position the UFO can catch the turtle.