André Bellaïche
7 articles published in Tangente
Games and ChallengesN°210Feb 20, 2023From Sissa to RSA
What use is there in raising numbers to powers, except for the fun of uncovering some arithmetical property of the natural numbers? Unexpectedly, this ancient computational art lies at the heart of modern cryptography and secure data transmission.
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Math for everyoneN°187Mar 25, 2019The envelope of a family of curves
Defining the envelope of a family of lines precisely is subtler than it appears. This becomes clear when we try to extend the idea to an arbitrary family of curves. René Thom's approach provides a way around the difficulties.
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Math for everyoneN°187Mar 25, 2019Knuth's octagons
The American mathematician Donald Knuth created TeX, a mathematical typesetting system based on Bézier curves.
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Math for everyoneN°187Mar 25, 2019Equilateral triangles from any triangle
There are at least two ways to derive an equilateral triangle from any triangle T—in other words, to obtain a triangle with the greatest possible symmetry from one that initially has none.
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Math for everyoneN°187Mar 25, 2019The envelope of a triangle's Simson lines
This delightful geometric property was familiar to French secondary-school students in the 1970s, although few knew how to prove it.
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Math for everyoneN°176May 24, 2017Henri Poincaré, geometry and... robotics
Mathematics, and geometry in particular, is an essential component of that most technical of fields: robotics. The concept of space, which the mathematician Henri Poincaré (1854–1912) explored in depth, lies at the heart of the robotics engineer's work.
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Math for everyoneN°174Jan 16, 2017An illustrious line of descendants
It all began with a football to which Euler's formula was applied. Why does the constant 2 appear on the right-hand side? To find out, we follow in the footsteps of Henri Poincaré, André Weil and… Alexander Grothendieck.
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