# Lecture 27

## 摺紙和數學 Origami and Mathematics

• 講者：林其鋒教授 香港中文大學 數學系
• 日期：2018年3月10日(星期六)
• 時間：上午 10:30 至 中午 12:00
• 地點：香港中文大學 何添樓 B6演講廳
• 語言：以粵語為主
• 講座簡報檔案下載 (pdf, 2.36MB)
• 簡介︰

Origami is the art of paper-folding. By unfolding an origami you obtain an intricate crease pattern on a piece of paper. How do we find the rules for these crease lines that allow us to fold a plane? The connection between geometry and origami seems clear, but tricky to write down precisely.

In this talk we will focus on one aspect of this connection - how to use origami to solve mathematical problems. We will see that by folding we can divide a piece of paper in equal fifths without using measurements, divide an angle into equal thirds, and even solve cubic equations.

Conversely, we will use mathematics to solve the problem of flat folding. That is, can you determine by looking only at the crease pattern that the origami is foldable and is also flat?

摺紙是一門藝術。當我們打開摺紙時，紙上會留下錯綜複雜的摺痕。然而我們如何才能從這些摺痕中找出摺紙飛機的規則呢？儘管幾何和摺紙之間有明確的聯繫，卻難以言喻。

在這次演講中，我們將討論如何使用摺紙來解決數學問題，例如在不測量的情況下將一張紙平分五份，將一個角度平分為三份，甚至求解三次方程式。

反過來，我們也可以用數學來解決摺紙的問題。 那就是，你能否只看摺痕，便確定有關圖案可被折疊並折平？