Let be a given regular 100-gon. Prove that if we take the union of two polygons that are congruent to , the ratio of the perimeter and area of the resulting shape cannot be more than the ratio of the perimeter and area of .
, 2021
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.