At Lin Dong's level, the first ten steps were quite perfect, and there were no mistakes.

But when the eleventh step comes out, the meaning of the auxiliary line becomes a curve, and it is two curves that are folded in half.

This means that if Lin Dong breaks through this line, then he will be trapped on this curve forever, and it will be difficult to get out, even if there is enough time in the IO event, but if he makes a mistake in this step, the delay will be very long, the national team has lost in the IO event in the past two years, and did not win the national team championship, if such a thing also happens on IO, then he, the head coach who leads the team, will have an unshirkable responsibility.

For Lin Dong, he was disappointed.

Exclude.

The few remaining players are not enough to compare with Fang Chao, Zhang Tiannan, Xiao Zizhan, and Jin Zixuan, and they still lack a little something.

Fang Chao also shook his head, Lin Dong's words he had the impression that his talent was good, and his talent was okay, and he even got a high score in the previous assessments.

But how to say it, he is like a car, a car with good performance, if it is modified, change to a horsepower engine, in this way, although this car will not reach the realm of supercar, but there is no problem with semi-supercar, right?

But Lin Dong did not have the mentality of being aggressive, and he was too decent, which was a fatal weakness for the mathematics competition.

Although the things that io emphasizes are all content within the scope of high school, over the years, every year's competition has been making breakthroughs, seeking change and innovation.

If you still stick to the rules, you will eventually be eliminated.

So in Fang Chao's view, Lin Dong basically missed the top six, because from the perspective of these players, the players that Professor Lin asked him to call up were basically favored by him by default, but if this level can't be passed, then unfortunately, after more than two months of hard work, you still haven't been able to make it to the national team.

Zhang Tiannan understood at the fourteenth step.

Jin Zixuan reacted at the fifteenth step.

Xiao Zizhan's words were suddenly at the seventeenth step.

The words of the others were still watching Lin Dong answer, and so far they had not found anything wrong.

Professor Lin's eyes fell on the players below, only one Fang Chao was the most satisfying to him, but only this one person, it is difficult to take the lead, the six people of the national team need strong soldiers, only in this way can they lead the national team to victory.

As for Zhang Tiannan, Jin Zixuan, and Xiao Zizhan's words are not bad, at least they have reacted, and if they sharpen themselves, they may not be able to become a weapon of the country.

"Professor...... I...... I can't do this anymore......"

Professor Lin opened his mouth and said, "Okay, Lin Dong, you can go down first." ”

Professor Lin didn't look at the four people who had basically been determined, because there was no need, and the main purpose of his question was to select the remaining two.

"I'll give you two more minutes......"

Before Professor Lin finished speaking, one of the female contestants raised her hand weakly and said, "Professor, I want to try." ”

"Oh?"

Professor Lin was stunned for a moment, and then said, "Chen Qin, you come up and try it." ”

"Yes, Professor."

Chen Qin is about 1.62 meters tall and a little obese, but after two months of morning exercise, the so-called obesity has now become a little strong, and she wears a pair of 525-degree polarized glasses above her eye sockets.

At this time, she walked up to the stage, picked up a piece of chalk, and then asked, "Professor, can I erase part of Lin Dong's answer and keep part of it?" ”

"Yes."

Professor Lin gave Chen Qin this permission.

Now that the training camp is coming to an end, everything that should be taught has almost been handed over, and the rest depends on the free play of the players.

Chen Qin got the order and directly erased most of Lin Dong's answer with a blackboard eraser, leaving only the first ten steps, and then drew a symmetrical triangle in the concentric circles.

butterfly theore！

You see, isn't that a beautiful name?

And its existence provides a lot of effective help in mathematics.

And it also has a Chinese name, which is the butterfly theorem.

The butterfly theorem, one of the most wonderful results of Euclidean plane geometry, first appeared in 115 years, by Horner to prove, and the proof of this theorem is numerous, and it is still studied by mathematics enthusiasts, and there are various variations in the exam.

Mathematics itself is ever-changing, so if you want to solve a problem, you must find the corresponding steps.

When the butterfly theorem came out, Professor Lin knew that Chen Qin would be the fifth player in the next and the first female player in the national team.

When this thing came out, Fang Chao knew that Chen Qin knew how to go about this question.

Thousands of roads lead to Rome, but with the knowledge of high school students to solve the problem that Professor Lin put on the blackboard, other methods are difficult to work, and there are many twists and turns, and this walk may not go to the south wall without looking back, but if you use the butterfly theorem, then many things will be logical.

But if you can think of the butterfly theorem, the difficulty of the problem itself has plummeted, but how many people can think of the butterfly theorem? It's so beautiful, so beautiful that people only notice its beauty and ignore its dangers.

"That's !! so"

"It's actually the butterfly theorem!!"

"If I had guessed that I had used the butterfly theorem, this problem would not have been difficult for me at all......"

"Ahh

"Professor Lin didn't let Fang Chao get up and answer because this question was used by him to test us, who can come up with it, then basically a place can be determined, Chen Qin, he is going to be the fifth player this time."

Lin Dong was stunned and looked at Chen Qin on the blackboard with the butterfly theorem to answer over there, those characters and mathematical symbols on the blackboard became beautiful under the butterfly theorem, a projection method, so that Chen Qin perfectly solved this problem.

If you give Fang Chao the difficulty of this question, it will only be 25 stars, which is a question with a fairly low score, because it is not difficult, as long as you master the skills, and even for Fang Chao, Professor Lin is simply a score question when he comes out of this question, but unfortunately he can't give a hint, otherwise, such a simple question will select countless players.

The significance of Professor Lin's question is lost.