So the group went back to the classroom.

Coincidentally, it was Li Lu's class in the afternoon.

In the end, he was still sat down, Su Chengyi looked at Li Lu's gloomy face.

"Put all the pens in your hands first."

Li Lu first patted the blackboard lightly, and when he saw that there were still people who didn't look up, he knocked hard again.

"Boom!"

There was a loud bang, and chalk dust fell.

Everyone sat with their backs straightened in fright.

"All looking at the question on the screen."

Li Lu enlarged the topic a little more on the computer, but the graphics were still slightly blurry.

She gave an impatient "tsk" and raised her hand to redraw a figure on the left and right sides of the blackboard.

Sometimes I really admire the ability of these teachers to draw on the blackboard, drawing a square is a square, and drawing a circle is a circle.

After finishing the painting, she turned around and saw that the eyes of her classmates were following her hands, and her eyebrows immediately twisted.

"Let me show you the title! Why are you looking at me? Do I have a question on my face? ”

Su Chengyi was secretly amused, took out a piece of scratch paper, did not use a ruler, and copied the graphics on the blackboard onto the paper.

In order to avoid blocking the blackboard, Li Lu stepped off the podium and began to patrol the classroom.

"Let's take a look at the question first and sort out my thoughts. I'll call two of my classmates to do it later. ”

As soon as she said this, there was a sudden inhalation in the classroom, for fear that she was the unlucky guy.

Just by the complexity of this figure, you can see that this is definitely not an ordinary difficult problem.

Zou Yong began to write hard from the moment the title appeared on the blackboard, looking like he was bound to win.

Chu Tianmian honestly drew a picture with a compass and a ruler, and Han Bing next to her was so worried that her face was wrinkled, and she was on the verge of giving up before she started to do it.

After Su Chengyi finished painting, he checked the points one by one to see if there were any mistakes.

Suddenly thinking of Chen Jinzhi's injured right wrist, he turned his head.

Chen Jinzhi, who was in a daze, was obviously taken aback by him, and looked at him with some astonishment.

Su Chengyi didn't speak, and put the scratch paper on her desk.

Chen Jinzhi smiled and whispered:

"I'm not going to do it."

Su Chengyi blinked his eyes and whispered:

"I'll teach you later."

"Don't talk to each other anymore! Do the questions well! ”

Li Lu banged the lectern.

Su Chengyi turned around with a smile, turned his pen and began to read the topic.

In fact, he has always felt that the complexity of the graph is not a bad thing, and the complexity of the graph represents the increase of the known conditions to some extent.

At the same time, it also represents an increase in problem-solving ideas.

"In triangle ABC, M is the midpoint of the side AC, and D and E are the two points in the tangent at the point of the circumscribed circle of triangle ABC..."

"Proof of: ∠BCQ=∠BAC."

Su Chengyi did not rush to make auxiliary lines, but first analyzed the basic properties of the entire figure according to the known conditions.

While reading and writing, the known conditions given on the question stem are gradually enriched a lot.

After this process, the idea of solving the problem is also about to come out.

It's not that hard.

Su Chengyi came to a conclusion on this question.

If he were to increase the difficulty, he would subtract one or two known conditions, for example, if it was necessary to prove that MD and AB were parallel, the difficulty would increase dramatically.

"Okay, I think it's pretty much the same, right?"

Li Lu clapped her hands, indicating that she was going to start pumping.

"No, no! I haven't finished reading it! ”

Han Bing quickly waved her hand, and she got up, and the others also shouted no.

"No, no!"

Li Lu's eyes widened like copper bells, and the classroom was so quiet that even the sound of needles falling to the ground could be heard.

At this time, whoever comes out again is a fool.

The atmosphere of silence and unity is broken by an abrupt voice.

"Teacher, can I go up and do it?"

Zou Yong seemed to have finally done it, he raised his hands high, his eyes full of anticipation.

Such a good student who cooperates with the teacher, Li Lu certainly has no reason to refuse, and nodded.

"Everyone is enthusiastic, Zou Yong is the first to take the lead, what about the others?"

Still no response.

Geometry questions are Chu Qianmian's absolute weakness, whether it is plane geometry or three-dimensional geometry, she has a headache when she thinks about it.

But she can do it too, but she doesn't want to go to the podium to do it.

When the classmates saw Chu Qianmian, who was still writing and painting with his head down, they all moved their eyes to Su Chengyi in the back row.

He held his chin and didn't know where he was looking, and his right hand was turning the pen boringly, and he didn't look like he was going to go up to do the question.

Of course, Li Lu also observed, and she had to sigh helplessly.

She said that she asked her classmates to do it, but of course she didn't want to ask her classmates to do it.

If you can't do it, what can you do when you go up? Isn't it in vain to hurt self-esteem when hanging there?

I didn't expect the few math top students who were a little more active on weekdays to be so quiet, and one of them was about to stuff his head into the desk.

There was only one student who volunteered, so she had to order another one that would be 100% done.

"Chu Tianmian, you go up and do it."

was named by Li Lu, Chu Qianmian reluctantly walked up, in stark contrast to Zou Yong, who was as confident as walking the red carpet next to him.

Su Chengyi put his eyes back on the podium and looked at the two people who were struggling to write with interest.

The problem requires that two angles be equal, so the easiest way to do this is to prove that the two triangles on which the two angles are located are similar.

Obviously, the two people on the podium are thinking in the same way, and even the auxiliary lines are doing the same thing.

"Pass Q to make a circle PQM tangent and cross MP at point C'..."

Chu Qianmian originally wrote well according to his own ideas, but Zou Yong next to him glanced at her, and suddenly said with a smile intentionally or unintentionally:

"Yo, squad leader, let's think of going together."

Chu was stunned, took a step back, and found that the two of them were indeed using the same method.

"Hey, the teacher asked us to come up and do it, I think we just want to see different ideas, it's a pity."

Zou Yong sighed and began to write again.

Chu Tianmian frowned and thought about it, turned around and took the eraser to erase the process and auxiliary lines that he had written halfway through.

Su Chengyi saw this in the back row and could probably guess what was going on.

Zou Yong, this guy has a set of yin and yang weirdness, will he change it himself if he collides with his ideas?

Chu Tianmian was already thinking about the second method just under the podium, but he was named on the stage before he could figure it out.

Now standing on the podium and doing calculations in private are two different feelings.

It was inevitable that he was a little nervous when everyone was paying attention, Chu Tianmian took a deep breath and decided to write out the ideas in his mind first.

"Let ∠QCB=x, from the angle theorem..."

When Su Chengyi saw the first sentence she wrote, he had already guessed her thoughts.

The idea is right, it's a little more complicated.

In this way, there is a high chance that she will make a mistake by thinking and writing as she is now.

Sure enough, halfway through the process, she took one wrong step in the equation, but as if she didn't know, she continued to calculate.

In this way, the equations that could have been ended a long time ago were written more and more, and the blackboard was about to be unable to fit in a large number of columns.