It turns out that both of these studies are related to some studies of the ancients.

Naturally, Mr. Li sold a pass and asked everyone: "Guess how the "hook", "strand" and "string" of this triangle are named?"

Then, everyone's speculation is naturally gossip.

After all, this content seems to be outside of most people's knowledge circles.

Yuan Li was the first to say: "Kitchen knives, right? There were many triangular kitchen knives in ancient times, and iron was very expensive. Therefore, you can only make money if you design a kitchen knife. ”

It seems that many people agree with Yuan Li's opinion.

Then, Yao Shun put forward a different opinion, saying: "The level of ancient iron-making tools is very poor, and I have not seen a triangular kitchen knife unearthed. ”

Wang Sheng immediately said: "I really don't know what this ancient iron kitchen knife looks like, after all, it will be oxidized as soon as it reaches the soil." ”

Hearing this, everyone laughed.

Naturally, Yuan Li understood, and what he said was no longer tenable, so he said, "Okay, then what other ideas do you have?"

Wang Sheng said with a smile: "I think eighty percent of them are made flags." After all, many flags in ancient times were triangular. ”

It seems that this idea is indeed more reliable, and many students applauded.

Then, Li Zengfan, who usually rarely spoke, stood up and said, "Why don't you take it literally? ”

Naturally, Mr. Li noticed that everyone's discussion seemed to be a little biased, so he made a quiet gesture.

Mr. Li smiled and said: "Everyone's ideas are very good, since you talked about the word 'share', let's start with the meaning of the word 'share'." In fact, the word 'share' is derived from the word '殳' (shu). And the meaning of the word '殳' is a blow blunt weapon. ”

After a pause, Mr. Li smiled and said, "Kicking is actually similar to using '殳' to strike." So the first thing to refer to is the legs. Then, over time, the 'thigh' part was used to refer specifically to the 'thigh' and 'shin'. ”

Listening to Mr. Li's explanation, everyone seemed to have entered a new world.

Teacher Li continued: "Okay, you don't have to worry about these examinations. Because there is actually no unification in academics, even if it is knowledge to enhance interest, the next thing is the main content, everyone listen to me well. ”

So, everybody pricked up their ears.

It turns out that in the Zhou Dynasty, long before the appearance of the "Nine Chapters of Arithmetic", the mathematician Chen Zi first used this concept when measuring the distance of the sun from us.

It seems that Mr. Chen Zi used the 殳 in the process, and at noon, the same length of the 殳 was inserted in different places.

Naturally, the length of the shadow of the 殳 inserted in different places will be different.

Next, mark the length of each shadow and the distance from each shadow to the one directly below the noonday shadow.

In this way, through these data, it is possible to approximate the distance from the sun to the earth.

In this process, as an experimental tool, the shadow gradually evolved into a right-angled side of the triangle "strand", and the shadow is called "hook".

After a pause, Mr. Li said with a self-deprecating smile: "The origin of this 'hook', in fact, I haven't figured out how to express it. After all, Chinese culture is vast and profound, with a long history. If any of you are interested in this aspect, you may wish to explore it systematically after university. ”

Naturally, everyone laughed when they heard this.

Then, Mr. Li continued: "As for the 'string', it was called 'Evil Solstice Day' before, and naturally, from the original model, it was the distance from the end of the shadow to the top of the shadow. ”

After a pause, Mr. Li smiled and said, "Have you noticed that the 'Evil Solstice Day' is 'string' if you read it faster." ”

Hearing this, everyone laughed.

Happiness and knowledge at the same time, everyone is simply happy.

However, it is still indispensable for students to get to the bottom of the matter, after all, when it comes to the distance from the sun, then the children naturally hope to finish how to measure.

Wang Sheng asked, "How can this be speculated? Just the length of these shadows? and the length of the so-called shadows?"

Other students also asked questions almost at the same time.

Teacher Li laughed and said: "I am only responsible for speaking, as for the solution of the math problem, I will still hand it over to your teacher Tan. Okay, hurry up, that classical Chinese is not finished yet. ”

So, the rest of the time is back to the chord diagram.

After Mr. Li's careful explanation, everyone realized that this seemingly complex string diagram is actually just an ancient mathematical proof and reasoning process.

To put it simply, content isn't a very difficult thing.

Most of the entire chord diagram is just there to state that the area of the small square in the middle of the big square is equal to the area of the big square minus the four triangles on the sides.

Naturally, in ancient times, the formulation of such a mathematical problem had to be so long, so the degree of difficulty in ancient mathematical research can be imagined.

Therefore, Zu Chongzhi and others must be geniuses among geniuses.

After the bell rang, everyone was more active than ever.

After all, the teaching of mathematics in classical Chinese has suddenly become a new popular event.

Some people have tried to adapt some math problems in classical Chinese.

Naturally, looking at such a topic, everyone was happy.

Wu Zhen and Wang Sheng couldn't laugh at all after taking a few questions for each other, and the students listening to it on the side laughed even more.

Then, the bell rang for math class, so Wu Zhenzhen didn't think about it anymore.

Teacher Tan walked in with a blank face and began to prepare the board book with chalk.

After all, the Pythagorean theorem is a very important test point and the basis for understanding trigonometric functions, so Mr. Tan's preparation is very sufficient.

Then, a few standard right-angled triangles appeared on the board.

"Okay, today we're going to start talking about the Pythagorean theorem. Hook three, strand four, Xuan five. This is something that is already in ancient math books, so let's study it well. Otherwise, modern people will not be able to catch up with even the ancients in this mathematics. Teacher Tan said with a smile.

Naturally, everyone laughed along.

After all, in previous Chinese classes, everyone has understood that in ancient times, learning mathematics was far less convenient than it is now.

Then, the original text of Zhao Shuang's chord diagram in "Nine Chapters of Arithmetic" was moved.

Although there are still a lot of original texts of this string diagram, everyone basically understands it after Mr. Li's explanation, so everyone can be regarded as a catchy read.

Teacher Tan looked at everyone's appearance and said with a smile: "Haha, like this today, it seems that Mr. Li's assist is quite good." Okay, so let's listen carefully. ”

Then, according to Euclid's method of proof, we will talk about it.

Indeed, Euclid's method seems to be easy to understand.

After making three squares on the three sides of the first right-angled shape of the board book, Mr. Tan said with a smile: "Obviously, the area of the two squares corresponding to the right-angled side is equal to the area of the square corresponding to the hypotenuse. ”

Wu Zhenzhen naturally understood what this meant, but some of the students still seemed to be confused.

After all, the concept is still relatively abstract.

Teacher Tan looked at everyone's situation and frowned.

It turned out that many students had empty eyes.