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Jinguo Hutong, Chongwen House.
After entering the house, Yu Hua went to the mourning hall first. The incense candles were burning on the incense table, and there was a layer of ashes underneath. He respectfully offered three incense sticks, bowed three times in succession, and paid homage to Yu Qinghe according to custom.
There were no mourning relatives or friends, and no funeral banquet arrangements. Yu Qinghe, who had a military style, repeatedly told Yu Hua to keep everything simple during his lifetime.
After adding incense and performing some etiquette, Yu Hua went to the kitchen, washed the iron pot and Chinese medicine, poured half a pot of ice water, put the Chinese medicine in cold water, found a Da Zhonghua match, took out one and lit it, and put the earth stove ignite.
This is the inconvenience of living alone. All tedious things need to be handled by hand.
"Read a book."
The flames of the earthen stove were strong, and Yu Hua sneezed when he felt the warmth and shook off a pool of snot. He felt a little bored. The excellent study state last night made people forget to leave. I don’t know if I can enter that kind of extremely focused study again today. state.
If you're bored, just read math.
He did as he was told and stuffed a piece of wood into the stove. Yu Hua got up and went to the bedroom. He picked up the arithmetic textbook and paper and pen tools, returned to the earthen stove, and read through the books by the light of the fire.
The progress last night was roughly three-dimensional geometry. The teaching knowledge points were derived from foreign higher education textbooks translated from Chinese to English. Some of them came from the United Kingdom and some from Princeton. They were basically the same as the weapons and equipment produced by the army at that time. They were rich in styles, but not the same. One is for Chinese mathematicians.
There is no way. In this era, the average level of domestic mathematics is far behind the world's mathematics level. Even catching up is a luxury, let alone parity.
"One of the axioms of solid geometry: If two points on a straight line are in a plane, then this straight line is in this plane. The second axiom: There is only one plane through three points that are not on a straight line..." Yu Hua Turning to the chapter on solid geometry, I silently recited the axioms of solid geometry that I had memorized in the past. The two memories in my mind continued to merge and transformed into the text structure of this era.
He read silently in his mind, and studied when he encountered doubts and puzzles. Yu Hua was happy, and the cold and fever did not seem to affect him.
Can learn!
Gradually, Yu Hua felt a surge of strength, and he once again entered a state of selfless learning. The content of the arithmetic textbook was easily understood, and the parts that seemed obscure and difficult yesterday became simple and common again.
After watching for a while, Yu Hua encountered a question about the angles formed by straight lines with different faces. EF are the edges AP of the triangular pyramid P-ABC and the midpoint of BC. PC=8, AB=6, EF=5, then straight lines with different faces What is the angle formed by AB and PC?
This question is of medium-to-high level difficulty. It was written by a teacher from Latimer Middle School in the UK. He held a pencil in his right hand and a piece of scratch paper on his lap, and he started calculating slowly.
Solution: Take the midpoint G of PB and connect GE and GF.
EF is the midpoint of AP and BC, PC=8 and AB=6 respectively.
Then GE∥AB, GF∥PC, GE=3, GF=4, the angle formed by the opposite right angle AB and PC is ∠EGF. In △EGF, GE²+GF²=EF is satisfied. Finally, △EFG is a right angle Triangle, and ∠EGF=90°, that is, the angle between the out-of-plane straight lines AB and PC is 90°.
"It worked out in one go. It's very simple. Continue." Yu Hua figured it out three times, five by five, and divided two. He wiped the runny nose with his hand and felt a great sense of accomplishment in his heart. He didn't dare to delay and continued. study.
Comfortable.
It's so comfortable. This kind of question about the angles formed by straight lines with different surfaces has always been in the state of heaven. Every time Yu Hua sees it, he will get dizzy and other symptoms. Fortunately, he can sleep well. Now he can do it all at once, and he has achieved success in his heart. The feeling is almost overwhelming.
Who can understand the joy of a poor student easily solving the exclusive questions of a top student?
Only Bingkuoluo can compare with it!
"Gulu gulu..."
While lighting the fire, I read the arithmetic textbook. After a while, white steam came out of the big pot. The water inside had boiled, and a faint smell of Chinese medicine overflowed from the side of the pot.
Smelling the smell of traditional Chinese medicine, Yu Hua adjusted the fire to medium fire, and then continued to read the question. The angles formed by straight lines with different planes belong to the calculation basis of spatial solid geometry. Next, it involves line-surface angles, dihedral angles and point-to-plane angles. Distance problems and other content are cumbersome and the questions are of medium difficulty. Most of the textbook test questions are from British and German middle schools.
However, the difficulty of this question is medium in relative terms.
For foreign high school students, these knowledge points involving basic solid geometry are not difficult. For domestic middle school students, these things are equivalent to ghost drawings, and many people have headaches when they see them.
Yu Hua is still good. After being tempered by the tactics of later generations, he is not only experienced in hundreds of battles, but at least has rich experience.
"Ah!"
After sneezing, Yu Hua rubbed his hands and became more energetic. The pain of cold and fever did not affect the learning efficiency. As he was immersed in efficient learning, more and more mathematical knowledge points were broken and entered into the depths of the brain. Storage, meanwhile, encourages the brain to become more and more excited.
dihedral concept,
Problems related to dihedral angles,
Calculation of distance from point to plane,
The distance problem between two parallel planes,
Find the distance in space using the method of equal volumes,
Straight line distance from different planes,
I boiled a pot of Chinese medicine in the middle and spent two hours. I easily mastered the calculation of spatial solid geometry of solid geometry and thoroughly understood the key points of knowledge covering almost the entire chapter.
Yu Hua woke up from a state of extreme concentration and selflessness. His head felt a little lack of oxygen. In his right hand was a piece of scratch paper filled with mathematical symbols and handwriting. This was already the tenth piece.
"Huh... let's take a break. It seems that this family is not only a bit talented, but also a top student with such efficiency in learning. But why does Yu Hua's grades in the class in my memory be average? It's strange, but according to this progress, I hope to get a perfect score in mathematics." Closing the textbook, putting away the pencil and scratch paper, Yu Hua took a deep breath to relieve the symptoms of hypoxia in the brain, rubbed his somewhat swollen forehead, and felt the mathematical knowledge points in his mind, full of expectation.
Now, with Yu Hua's mathematics level, he is taking the college entrance examination again. He is sure that his level in mathematics is at least 90 points, with an increase or decrease of no more than five points.
If the score falls by one point, you will have to worry about it with the marking teacher.
Calculated based on the current learning efficiency, I can review the main subject of mathematics in one month. Physics, chemistry and biology take about one month. Chinese and Party literature are a bit of a headache. With my traditional Chinese skills, it will take at least two months. English We also need to keep a schedule and learn Japanese. The more we learn, the better.
In addition, arrangements must be made for Yu Qinghe’s burial.
Yu Hua thought silently, got up and went to the stove, picked up a porcelain basin full of Chinese medicine, poured it into a small bowl, and drank it in one gulp.
After drinking the medicine, Yu Hua was going to go to bed to rest for a while, and then went to work on Yu Qinghe's funeral in the afternoon.
"Dong dong!" At this moment, there were sudden knocks on the door of the house.
"Is there anyone there?" A small voice came next.
