Chen Jinhua sat on the rickshaw all the way, waving to the group of people on the street who couldn't wear autumn clothes, looking at people's envious expressions, out of the limelight, and his heart was very happy.

I didn't know that this move made Gong Deming want to push him off the car many times, but it was too bad to do it with someone like Chen Jinhua......

"It's a shame not to sit in the same car with you next time."

Gong Deming put down this sentence, didn't bother to say hello to Guo Chun and Bao Guowei, and walked quickly to the door of the school angrily and disappeared into the crowd.

This made Chen Jinhua scratch his head: I don't know what made this one angry.

It was the end of the lunch break, and it was about to be the time for class, and the students at the entrance of the school were either holding books in their hands, or holding candy people, chatting, and walking inside, which was very lively.

Probably because of the very eye-catching hairstyle after wiping Si Dangkang, Bao Guowei attracted many people's frequent side eyes: Could this be a new young gentleman? Looks a little handsome.

The nearest road to Building No. 1 is to go from the west, and halfway through, a vacant lot on the path on the west side of Bao Guowei was planted with three friends of the year: "pine", "bamboo", and "plum".

A banner was also raised: Welcome to winter and praise the three friends.

Winter is coming!

Is winter really coming?

"Bao Guowei! What are you doing with this thing? It's 1:15, and it's almost time for class. ”

Guo Chun saw that Bao Guowei was a little stunned, patted him on the shoulder, and urged him to leave quickly.

"Let's go!"

In the fierce autumn wind, bright red banners fluttered in the wind.

Chen Jinhua was left there alone, he couldn't come back to his senses, touched the exquisite and thick banner, and looked at the shabby cotton clothes on his body: it was a little white, and there were oil stains on the placket, forming small spots.

"Welcome the winter and celebrate the ...... of the three friends"

……

It was less than 1:20, and there were still more than ten minutes before class, and the class was already full.

Most of the students in the new-style school are children of wealthy families, and naturally there is no lack of communication skills, and after a period of getting along, they have been able to chat, so when the back row by the window F3 entered the class, it was already full of people.

"Bao Guowei, can I ask you this question?"

An Shuzhen heard the sound of the chair rubbing against the ground in the back, and knew that the three brothers in the back row had already taken their seats—naturally the classmate who was good at science was also there.

"What's the problem? Let's talk about it. ”

An Shuzhen turned around, and wanted to show "Geometry General" to Bao Guowei, but suddenly saw that the person in front of her seemed to be much more pleasing to the eye than before?

"You're wearing makeup!"

After saying this, An Shuzhen gently covered her mouth, she really shouldn't say this.

"Si Stankang."

"What?"

"I wiped Si Dankang, head oil Si Dankang, if you have any questions, hurry up and ask."

Bao Guowei was a little helpless, Guo Chun had been asking this question all the way, and it seemed that the effect of the hair oil was too good.

An Shuzhen was skeptical when she heard Bao Guowei's explanation, but it didn't matter:

"sinA+sinB=2sin[(A+B)/2]cos[(A-B)/2], how is this formula derived?"

Looking at the part that An Shuzhen pointed at with his finger, Bao Guowei fell into deep thought, and he felt that he was probably dreaming: "When was this thing taught?" Could it be that Mr. Shen came to the classroom during the lunch break to make up for everyone? ”

This is clearly the formula for the sum of the differential product in trigonometric functions, but Bao Guowei didn't bother to delve into it, took out a pencil, and took out a piece of scratch paper:

"You know the sine formula for the sum and difference of the two angles of a trigonometric function, right?"

"Know, sin(A±B)=sinAcosB±cosAsinB; cos（A±B）=cosAcosB±sinAsinB； tan（A±B）=tanA±tanB／1±tanAtanB。 ”

Hearing An Shuzhen's answer, Bao Guowei confirmed that she had really learned this step, and wrote as she spoke:

According to the formula you just mentioned, we can know that sin(A+B)=sinA*cosB+cosA*sinB, sin(A-B)=sinA*cosB-cosA*sinB. We add the two formulas to get sin(A+B)+sin(A-B)=2sinA*cosB, so, sinA*cosB=(sin (A+B)+sin (A-B))/2"

"And in the same way, according to ......"

It's time to start chanting! Western classics! Guo Chun, who was next to him, covered his ears when he heard this, but his eyes couldn't help but look over, looking at the increase in the number of letters on the paper, he couldn't help but shrink his pupils, and was shocked, this is something that humans can remember?

……

Chengnan, Lao Zhang's barber shop.

Lao Zhang has always been reluctant to give up in recent days, and he is always absent-minded when giving haircuts.

The reason is that he found that his son Zhang Siwu has always disappeared inexplicably for a while in recent days, especially at night, often staying up all night, and often bringing some money to subsidize the family.

According to Zhang Siwu, it has been cold recently, and there are fewer people working night shifts, and people are afraid of getting sick from the cold, so the salary is much higher than before, and they have to go out to work more to subsidize the family.

Lao Zhang is a little unbelieving, now there are so many people who come to Gusu to flee, where will there be a shortage of people to work? It's the work of going up and down the knife mountain and going down to the oil pot, as long as you can send a few more big buns, then there are people to do it.

Besides, even if the salary is high, other people's families are afraid of getting sick, and their own sons will not get sick? Lao Zhang has not been dissuaded: four or five, don't always mess around outside.

Zhang Siwu always promised, and after a few days, he will still go his own way.

When did this begin......

A thin man in his forties and fifties entered the barbershop, shook his pocket, made the sound of coins colliding, and sat straight down on the chair where the hair was cut.

The meaning is clear: cut your hair

This man's hair was so long that it covered his eyes, and he looked like an "old coal" on the street.

The so-called "old coal" refers specifically to the man who abducts and sells children, and if it is a woman, it is called "old manchu".

Covering the thin man with a scarf, Lao Zhang picked up the scissors and cut his hair with a click.

The skill of cutting hair seems to be engraved in Lao Zhang's instinct, and "thinning" and "thinning" are not a problem......

"Shhh What the hell are you doing! ”

The thin man gasped, the reason was that when Lao Zhang cut his hair, the scissors poked his scalp.

"Huh! Excuse me! Didn't pay attention! Didn't pay attention! ”

Lao Zhang hurriedly apologized, this is a new guest, be polite.

"No, you've got to lose money!"

The thin man was unrelenting, his eyes narrowed, his eyebrows wrinkled a few lines, and his nose was folded into a lump from the tip of his nose to the bridge of his nose, looking extremely angry.

He put his hand on his scalp and touched it, and then put it under his nose to see: there was no blood, only mud in his nails.

The thin man was a little disappointed: if this scissors could poke a small hole in his brain and bleed hard, he could ask for more money, and coincidentally he could add an extra shirt to himself.

The thin man unwillingly put his hand on his scalp again and touched it again, and quietly buttoned it with his nails, trying to pull out some blood.

"Blood! Bleeding! ”

Looking at the blood stains on the edges of his nails, the thin man screamed excitedly.

"You picked it out yourself, it has nothing to do with me! There is no mark on this scalp at all, don't give me this trick, your grandfather and I have eaten more salt than you have ever eaten! ”

Lao Zhang knew that he had met a leper, and he had been in business for so many years, and he had seen all kinds of people.

"Phew!"

An angry shout came from outside the door.