Baltic Way 2023 · Problem 9
Combinatorics
Determine if there exists a triangle that can be cut into 101 congruent triangles.
When you’re ready
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Review
Topics
Pigeonhole and extremal arguments
Solutions
Solution
Answer: Yes, there is. Choose an arbitrary positive integer and draw a height in the right triangle with ratio of legs . This height cuts the triangle in two similar triangles with similarity coefficient . The largest of them can further be cut into smaller equal triangles by splitting all sides in equal parts and connecting corresponding points with parallel lines. Thus a triangle can be split into equal triangles.
The figure shows this for , but in our problem we must take .

Contest context
Results from Baltic Way 2023
10 teams
- Mean score
- 0.5 / 5
- Scores of 4 or 5
- 1 / 10
- Estonia
- 0 / 5
Score distribution
09
10
20
30
40
51
All team scores
| Team | Score |
|---|---|
| Germany | 0 / 5 |
| Sweden | 5 / 5 |
| Lithuania | 0 / 5 |
| Poland | 0 / 5 |
| Estonia | 0 / 5 |
| Latvia | 0 / 5 |
| Norway | 0 / 5 |
| Denmark | 0 / 5 |
| Finland | 0 / 5 |
| Iceland | 0 / 5 |