今天闲来翻书看了道题： 一个数列： 1，2，4，7，8，11，14，16，17，19，22，26，28，29，41，44 下一个数是什么？（点击阅读全文有答案）
Tag Archive > 数学
证明：根号2是无理数（from ‘plus magazine’)
The square root of 2 is irrational The first thing you might ask if you saw this definition is – are there any irrational numbers? How do we know that Ö2, say, is irrational? To prove that Ö2 is irrational, suppose the contrary, namely that it is rational, so that there are integers p and [...]
treat or trick to your brain:geometry problem
Here is a fun one: The triangle ABC is isoseceles, with angle(ABC) = angle(ACB) = 80°. We draw now two segments inside the triangle. First, we choose the point D on segment AC such that angle(CBD) is 60°. Also, we choose the point E on AB, where angle(BCE) is 50°. We now extend DE until it [...]