好的数学之几何篇

欢迎回到关于好的数学的研究。今天我们研究几何方面。

研究一：球的体积公式推导

方法：利用圆柱体积公式推导。

右图是一个圆柱体，圆柱中有一个球体。

我们都知道圆柱的体积公式是，

在本图中把h代换，变为：，又因球体积是圆柱体积的，所以简化式子：

 即球体体积公式。

虽然还有一种推导办法，但难以理解和应用，在这里就不说了。

研究二：七角星画图及（n+2）角星画图。

类似右图的图形就是七角星，画法如下图：

第一步：类似五角星顺着已经有的边顺时针或逆时针靠着画就行了。第二步：按顺序画即可。

（n+2）角星画法：大家注意到了没有，通过五角星可以推出七角星哦！

这是画七角星的前两部，这正好是五角星哦！最后再添两笔就成了七角星。最后两笔怎么添？找一个右下角连接两点即可。

同理，用七角星推理画出九角星也是同样的方法。

这便是我们这次的全部研究了，希望大家继续研究！

经典阅读二班      许智城

第二篇：写作阅读报告

Book Report On《Just One Look》

《Just One Look》is a world-famous mystery fiction. It has translated into many languages .It is written by Harlan Coben, It was published in 2004.The writer Harlan Coben is the first author who has ever won all three major crime fiction awards in the US. The book was published in 2004.

The leading character of the book is a woman named Grace Lawson .She lives a happy life with her husband Jack and two children .However, an ordinary photo makes her life happen to turn the world upside-down change .An vocal concert accident that happened many years ago caused a terrible event-there were 18 people was trampled to death ,in this stampede tragedy, Grace lost parts of her memory. Many years later, When Grace flushes her family photos , she finds that there is a photo that was taken at least 20 years ago. There are five people in the photo, one of the people looks like her husband Jack, Grace does not know how the photo get into her new photos .When she show the photo the photo to her Jack, Jack denies that he is one of the men .At that night, Jack run away from home and takes the photo away without any explanations .Grace does not know where Jack to go and why Jack wants to go .At the same time, a grim killer come to her town, some innocent people are killed. She turns to the police , for this is a very complex law case, the police refuses to give assistance, and her neighbors can not help her too. So Grace must face the tragic and dark fact alone. In the long time without Jack , she takes heavy responsibility to take care of her children. As time goes by , there are more and more mysteries in the bottom of her ,more and more doubts crowd in her heart about her marriage with Jack .At the same time ,she finds that there are other

people are looking for Jack and the picture, including the brutal killer. In the process of finding truth , Grace finds a series of murders were schemed by victim that was hurt in stampede tragedy that happened many years ago. Then Grace finds her husband has died 15 years ago. She wonders who is the man that lived with her for the years .In the hard and long process of finding truth , Grace unexpectedly finds that she has enjoyed ten years of false happiness, she has dropped into a big hoax that has been schemed early. all of the mysteries make up a mysterious death jigsaw puzzle picture . The truth is to bury a secret that related to many people , It causes a series of killing and other secrets.

this is the first time that I have read mystery fiction .The title of the fiction was translated into Chinese words ,It means “the jigsaw puzzle picture of death”,there are several explanation about the title :either “just one look ,you will addicted to it ”or “just one look, you will be surrounded by horror and fear”.just three simple words ,the meaningful definition hidden behind it. This fiction is a magical book, the compact layout, complex conceive ,the complicated relationship between characters … All the enigmatic clues was arranged clearly by writer .When I was reading , I sometimes felt living in the fog, sometimes felt gradually clear .All of the plots are filled with subtle suspense atmosphere .The fiction is filled with fine

description of the emotion, the causes of the fiction though just a photo, the whole story have seen Grace's deep love for Jack 、which also mixed with Shalin's indifference to her husband and Shalin's ambiguous emotion to her neighbor 、and protection and caring of Jack for Grace and Grace's deep love for her children …Although there are a few descriptions in the whole book but they add a lot of warm emotion .The conventional mystery fictions are filled with surreal fantasy or violent behavior to meet with our curiosity .Compared with conventional mystery fictions, this fiction is base on daily life.

I will recommend this fiction to my friends , for the logic of the fiction is strict and tight. It challenges our intelligence. I felt I Became more smart and my logical thinking is more excellent which could help us do better in chemistry and physics.

How fabulous this fiction is.