A regular hexagon PROFIT has area 1. Every minute, greedy George places the largest possible equilateral triangle that does not overlap with other already-placed triangles in the hexagon, with ties broken arbitrarily. How many triangles would George need to cover at least of the hexagon's area?
Solution
It's not difficult to see that the first triangle must connect three non-adjacent vertices (e.g. POI), which covers area , and leaves three 30-30-120 triangles of area each. Then, the next three triangles cover of the respective small triangle they are in, and leave six 30-30-120 triangles of area each. This process continues, doubling the number of 30-30-120 triangles each round and the area of each triangle is divided by 3 each round. After triangles, the remaining area is , and the last triangle removed triangle has area , so this is the minimum number necessary.
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