In regular hexagon A B C D E F, A C, C E are two diagonals. Points M, N are on A C, C E respectively and satisfy A C: A M=C E: C N=r. Suppose B, M, N are collinear, find 100 r^{2}.
In regular hexagon A B C D E F, A C, C E are two diagonals. Points M, N are on A C, C E respectively and satisfy A C: A M=C E: C N=r. Suppose B, M, N are collinear, find 100 r^{2}.