认识 HTML 超文本标记语言（HyperText Markup Language，简称：HTML）是一种用于创建网页的标准标记语言。利用其编写的文件放在 Web 服务器上，任何浏览器就能通过互联网得到相应的 Web 页面。 HTML 不是一种编程语言，而是一种标记语言 (markup language) 标记语言是一套标记标签 (markup tag) HTML 使用标记标...

期末考试前的复习草稿，写的比较随意，有时间考虑再整理成电子版（随时会鸽）。

期末考试前的复习草稿，写的比较随意，有时间考虑再整理成电子版（随时会鸽）。

1. Introduction The addition of angular momenta is a fundamental problem in modern physics. For instance, when dealing with systems composed of multiple particles, such as atoms with multiple elect...

To be continued…..

Consider two infinite grounded metal planes with an angle $\alpha$ between them, as shown in the following figure. A point charge $Q$ is located at $(r_0,\phi_0,0)$ in cylindrical coordinates, wher...

Question: Try to solve the following integral: [\int_0^1 \frac{x \ln(1+x)}{1+x^4} \, \mathrm{d}x.] I have answered this question on Zhihu, you can find it here. Solution: We define $ f(z) = z \l...

Question: Try to solve the following integral: [\int_0^{\frac{\pi}{2}} \frac{\ln\cos x}{x^2 + \ln^2 \cos x}\, \mathrm{d}x.] This question has been solved on Zhihu, you can find my solution here. ...

Question: Try to solve the following integral: [\int_0^1 \int_0^1 \frac{y^2}{(x^2y^2+1+2y^2)(y^2+1)}\, \mathrm{d}x\mathrm{d}y.] I have already solved this integral on Zhihu, and you can see my so...

Record my mathematical answers on different Q&A websites, including various integral and series calculation questions.