2021 JMPSC Invitationals Problems/Problem 2
Contents
[hide]Problem
Two quadrilaterals are drawn on the plane such that they share no sides. What is the maximum possible number of intersections of the boundaries of the two quadrilaterals?
Solution
We find that it is possible to construct the maximal points, where each side of one quadrilateral intersects all four sides of the other quadrilateral.
~samrocksnature
Solution 2
Take two concave quadrilaterals. Call two lines "somewhat parallel" if the different in their slopes is less than . An arrow has approximately
lines which are "somewhat" parallel, which means
arrows that are
to each other form
intersections.
~Geometry285
Solution 3
A line can intersect other non-parallel lines
times. If we draw
quadrilaterals with non-parallel sides, it would then be possible to get
intersections.
~Mathdreams
See also
- Other 2021 JMPSC Invitationals Problems
- 2021 JMPSC Invitationals Answer Key
- All JMPSC Problems and Solutions
The problems on this page are copyrighted by the Junior Mathematicians' Problem Solving Competition.