Hello. I have a problem that I can't solve: 1. The problem statement, all variables and given/known data A boat (boat one) is in the position (0,0) and he sees a friend's boat (boat 2) which is in the position (a,b) and sails with velocity ω2 in a straight line (I mean, a is always the same coordinate and b changes with time: b = b0 + ω2*t). Boat one has to approach at least at a distance r for being seen by boat 2. If boat 1 starts sailing diagonally with velocity ω1, ¿what angle is the correct for approaching the objective at distance r in the less time posible? 3. The attempt at a solution I think coordinates of boat one change with this equations: x= ω1cos(angle)*t and y = ω1sin(angle)*t; I have calculated the disance: d= √((x-a)^2 + (y-b)^2), then set it to r, put everything in fuction of t, derivate and set to cero but it's a way I think it's not correct because the result looks like a monster. I have to give the result in fuction of the problem's parameters. I have thought maybe we could do it with ODE or with Hamilton... but I don't know. Thank you for every suggestion.