It was a cloudy morning, and a cool breeze was blowing on the campus of No. 4 Middle School.

In the classroom of Class 8 of the second year of high school, there are more than 40 people, and the head teacher is sitting in front of the first row of classmates, and the students standing on the podium are also classmates.

The young man held a white pen in his right hand and a test paper in his left hand, his figure was tall, and he was indifferent, with no nervousness on his face. Fluttering, leisurely, and admirable a young man.

If the picture freezes for a moment and is static, it can probably be described like this.

But the dynamics are not,

I saw that the teacher in the corner suddenly stretched out his hand and interrupted, "You also want to talk about the concept, I will start the lecture directly from question 8?"

Haven't heard of it, don't know.

The students sitting below are also listening to the class with interest, the middle school years are too boring, and any difference can bring happiness to everyone.

A Yilin magazine can be read several times, and its tastelessness can be imagined.

So today, Wen Xiaoguang gave a lecture, and everyone was still happy.

Except for those who are secretly jealous of Wen Xiaoguang's good grades and handsomeness, there are more than forty people, there must be such people.

For example, Jiang Weiliang, who is usually blind to Wen Xiaoguang, has long been inflated by anger to the lungs.

So he arrogantly thought that Lao Tzu just didn't listen.

At this time, I turned my head and looked at Pei Xiaobai's face, and I felt that all my internal organs were burning, life is so helpless, Sao Nian, you have to get used to it as soon as possible, anyway, there are many people who are born with it, and the other part of them don't die until they die.

"Then I'll start with the first question...... "Wen Xiaoguang didn't go to the tired old road to raise the bar, this man's heart is now fragile and ruthless, and he can collapse if he is not careful.

The college entrance examination in the province where Xianzhou is located has canceled the multiple-choice questions, because the multiple-choice questions are easy to guess the answers, and the devils don't give this opportunity, don't guess it, it's all fill-in-the-blank questions.

Each question is worth 5 points, and getting one question wrong is like the feeling of Lao Lu seeing himself lose a hair.

"An equation that passes through the point (2,1) and is parallel to the straight line x-y+2=0. ”

Wen Xiaoguang really doesn't know what to talk about in this question, it's really a concept, the slope of parallel straight lines is equal, what else do you have to say?

Well, take care of it not so well.

"According to the theorem, a parallel line can be set to x-y+a=0......"

Lao Lu suddenly began to command again, "This question is simple, and there are not many people who have misunderstood, so there is no need to talk about it." ”

Wen Xiaoguang: "......"

He gave a 'you experience it yourself' look.

What is this for?

If you don't talk about it, let me talk about it, and if you talk about it, you won't talk about it.

Many classmates couldn't help but laugh out loud when they looked at his expression.

"Teacher, why don't you come?"

Lao Lu's buttocks were stained on the bench, which was called a comfortable, "You come, you come, I'll just say it, the first few questions are a little simple." ”

'Wow' Wen Xiaoguang shook off the test paper, "Let's look at question 8, the hyperbola,"

Lu Yonghua, "......"

Mom sells batches.

"It is known that the right focal point of the hyperbola x^2/a^2-y^2/b^2=1(a>0,b>0) is F, and the perpendicular line from F to its asymptote is P. If the midpoint of the line segment PF is on this hyperbola, find the eccentricity of this hyperbola. ”

This is a Dowlah sub-question, and those who are not solid in learning will fall behind those 5 points.

Like Dai Weiyi and Jiang Weiliang, who are not very good at mathematics, this one is a red cross.

Wen Xiaoguang drew on the blackboard and made a regular ellipse, "I'll talk about my approach to this question, if there is a mistake or better, please add it." ”

"First draw the asymptote line y=b/ax, get bx-ay=0, set the right focus F(c,0), then through the point F, you can lead the perpendicular line y=-a/b(x-c) to the asymptote line. ”

"The coordinates of its intersection with y=b/ax P are (a^2/c,ab/c)......"

"Finally, simplification yields c^2/a^2=2, so the eccentricity e=c/a=root number 2."

It's difficult, but it's actually okay, just ask for C/A, it's not difficult, people who don't have a strong foundation don't even know how to calculate the eccentricity.

In fact, there are already some tricks, and it is much easier to calculate the ratio directly than to find the values of c and a respectively, and then divide them to get the result.

But there are always some people who are really hard calculated.

Lao Lu sat down and nodded repeatedly, this question shows his mathematical skills, not a fool.

There are also students below who show the appearance of 'I see', and it turns out that there is this kind of algorithm.

Jiang Weiliang looked at the calculation equation of the written project and copied it down with tears.

If you don't copy it, you can't do it, and if you go back and revise this test paper, you have to collect it again, and you can't send it down, and you can't hand it in.

"Do you have any questions?" Wen Xiaoguang asked the group, "If you have any, you can bring them up." ”

There is no sound, this is middle school mathematics, and many questions are not difficult to write down, but you can't think of it.

Lu Yonghua also chimed in, "The easiest way to solve this problem is like this, let's take a look." ”

"Wow......" Everyone heard the teacher's words, and they no longer had any doubts.

Jiang Weiliang turned his head to look at Pei Xiaobai again, the girl held her chin and smiled stupidly, almost drooling out!

Angry!

"I have!"

Wen Xiaoguang raised his eyelids and found that it was this kid, and there was something strange in his heart, but he still said, "Well, you say,"

Jiang Weiliang choked, damn, in fact, the process is written quite clearly, and the operation is nothing more than junior high school content such as item transfer.

This is what you want to ask suddenly......

“...... How did you come up with the idea of taking the asymptote in the first place?"

Wen Xiaoguang raised his eyebrows, put the test paper on the podium, and asked me how I thought of it without asking the steps, I would look at it, how else did I think of it, I don't know why you can't think of it!

It's the same as asking why your surname is Jiang, stupid!

Wen Xiaoguang looked at the blackboard, and then said: "This kind of skill-based question, the first step is really not easy to think of, you ask me how I came up with it, in fact, I didn't think of it, I also did a lot of questions, it should be said that after doing a lot of exercises, so I only felt when I saw it." ”

Dai Weiyi: ???

Doing a lot of practice?

"So if you want to ask why, there is actually no serious answer, if you want to say that there is, it is to do more questions. ”

To be reasonable, what Wen Xiaoguang said is 100% correct.

Lu Yonghua also nodded in agreement, "Yes, mathematics requires a certain amount of practice, and it will naturally be easy to see more questions, Jiang Weiliang, you go back and practice appropriately, and strive to do it next time." ”

Saying that, Lao Lu stood up, and when he heard this, he was basically relieved, "I'll go to the bathroom, you continue." ”

Wen Xiaoguang responded, and then looked up at Jiang Weiliang's bitter face at that moment, and couldn't help but want to laugh, boy, do you go on again, believe it or not, get yourself a bunch of practice test papers?

So that you won't be lonely when you go home at night.

Jiang Weiliang's brain was blue, where did he, a scumbag, ever think that there was such a thing.

Looking at Wen Xiaoguang again, he suddenly blinked his left eye, and he still had that hateful smile!

Ahh

"And what about our next question?" he asked with a smile.

Jiang Weiliang sat down with a shrunken contraction.

Lu Yonghua was not there, the students relaxed a little, and he also let go a lot.

"Although hyperbolas and ellipses are not as basic and important as functions, they are also particularly critical places in geometry. Wen Xiaoguang made a joke with him.

Some people were not convinced, taking advantage of the teacher's absence, "Then how important is it for you to talk about it?"

Wen Xiaoguang looked for the source of the voice, and a second man behind him who was jealous of his appearance was called Zhang Hetian in his impression.

"How important?" he thought of making the fools understand in as simple words as possible, "Let's put it this way." In the history of mathematics, when the parallel axioms of Euclidean geometry were questioned, two non-Euclidean geometries were born, elliptical geometry and hyperbolic geometry. How important is that, you say?"

Jiang Weiliang: ??? count...... History of Mathematics?

The other classmates were also stunned, Pei Xiaobai came back to his senses from the nymphomaniac and asked the tablemate: "Liya, what did he just say?"

"Don't blow it, when did you understand the history of mathematics?"

"That is, elliptical geometry?"

......

Wen Xiaoguang can tolerate others saying that he is not handsome, because he is handsome if he says it or not.

But he can't stand being questioned by people who question his academics, learning is something he values more than his appearance in this world.

In 1854, Riemann replaced Euclidean parallel axiom with the axiom that "a point outside the straight line, no straight line is coplanar with a known straight line and does not intersect", and created another non-Euclidean geometry. ”

Speaking of which, the classroom was a lot quieter.

Wen Xiaoguang pinched off the head of the chalk, and while continuing, he briefly wrote out a formula.

"Mathematicians before Riemann only knew that there existed on the surface S in the three-dimensional Euclidean space E3 with the induced metric ds²=Edu²+2Fdudv+Gdv², i.e., the first elementary form, but did not realize that S could also have a metric structure independent of the three-dimensional Euclidean geometry. ”

Riemann realized the importance of distinguishing between induced metrics and independent Riemannian metrics, thus freeing himself from the constraints of classical differential geometry surface theory, which was limited to induced metrics.

"Riemannian geometry, or elliptical geometry, was created. Do you understand?"

......

Lu Yonghua came back from the toilet, satisfied, I was not there, and the classroom was quite quiet.

Then he glanced at the blackboard and was stunned for a moment, which read: Induction metric ds² = Edu² + 2Fdudv + Gdv².

Many of his classmates also looked at him.

He doesn't understand it either!

"It's ...... What's the question?"