Geometric Passe-muraille

A 3D regular hexahedron solid (cube) passing through a 2D plane:

Puzzle Creation for Associations

For 20 years, Archimedes Lab has created visual puzzles for the association RMT (Rallye Mathématique Transalpin). You can use them for your personal projects or for your math class. Enjoy!
Depuis plus de 20 ans, Archimedes Lab crée des puzzles – qui sont utilisés comme des attestations – pour l’association RMT (Rallye Mathématique Transalpin). Merci de respecter les copyrights. Amusez-vous bien!
Association RMT: http://www.armtint.org

Ellipse-Tracer

Two moving tangent circles can trace ellipses

Sprouts Game

All possible ways a game of “Sprouts” with two initial dots can evolve. Sprouts is a paper-and-pencil game that can be enjoyed simply by both adults and children.

Coxeter Disc

Infinite flavor in a finite fruit pastry space!

Infinite Pythagorean Triplets

Consider the following simple progression of whole and fractional numbers (with odd denominators):
1 1/3, 2 2/5, 3 3/7, 4 4/9, 5 5/11, 6 6/13, 7 7/15, 8 8/17, 9 9/19, …
Any term of this progression can produce a Pythagorean triplet, for instance:
4 4/9 = 40/9; the numbers 40 and 9 are the sides of a right triangle, and the hypotenuse is one greater than the largest side (40 + 1 = 41).

A curious right triangle

The sides of a pentagon, hexagon, and decagon, inscribed in congruent circles, form a right triangle.