MathDB

4

Part of 2015 Greece National Olympiad

Problems(1)

From A to C

Source: Greek MO 2015

3/22/2015
Square ABCDABCD with side-length nn is divided into n2n^2 small (fundamental) squares by drawing lines parallel to its sides (the case n=5n=5 is presented on the diagram).The squares' vertices that lie inside (or on the boundary) of the triangle ABDABD are connected with each other with arcs.Starting from AA,we move only upwards or to the right.Each movement takes place on the segments that are defined by the fundamental squares and the arcs of the circles.How many possible roots are there in order to reach CC;
combinatorics