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Second Round, March 2019

Netherlands 2019 geometry

Problem

In a square of side length we draw lines from each vertex to the midpoints of the two opposite sides. For example, we connect to the midpoint of and to the midpoint of . The eight resulting lines together bound an octagon inside the square (see figure). What is the area of this octagon?

problem
Solution
Final answer
2/3

Techniques

Cartesian coordinatesConstructions and loci