Is it possible to put on the plane points, so that with vertices from these points to construct parallelograms of area ?
Solution
We shall prove that it is possible. We consider two parallel lines with distance . We put on each of them points such that every two successive of them have distance . Then we have in the line segments of length and in the line we have also unit segments. Any pair of unit segments having members from both lines gives rise to a parallelogram of area . Therefore we have totally parallelograms of area .
Want a route through all this instead of an archive? The track
puts 2,000 problems in a working order, from AMC 10 level to the IMO shortlist.