Thursday, May 20, 2010

Fox 289

Commonality of the result may imply the existence of a simply solution, which we don't know.
Good luck!


  1. Join the centre of the circle to the top right corner, then n is the shortest and m/n equals the Golden Ratio (1+sqrt5)/2.

  2. golden ratio is indeed the right answer, but not achieved at the point where n is minimal. For an obvious reason: for any parameterized P(m(t),n(t)) representation, when n'=0, m'<>0 and n>0 therefore (m/n)' = m'n-n'm/n^2 = m'/n <> 0. Hence ratio m/n cannot be extremal when n is.

    1st method: O being the center of the circle, take P such as cos(angle(OP,horizontal)) = 2/3.

    2nd method: draw a line from bottom right corner through the point where n is minimal (as constructed previously). This line crosses the circle in a second point which is the requested point.

    Unfortunately, all these results come from differential calculus and trigonometry. Any idea for a geometric justification?