So, that's cosine theta d theta. And, well, if you do things with substitution, which is the way I do them, then you should worry about /2 the bounds for theta which will be zero to pi over two.
所以dx=cos,θdθ,如果用变量替换法来做,接下来就要考虑θ的取值范围,它是从0取到π
Many a time we don't know what we should do, but we still don't do it when we knew what we should d...
很多时候我们都知道要做什么,但是知道了该怎么之后,我们仍然不去做。
Some of the things I said--you'd probably say, well I should have known that an insurance company would have to do that, but it isn't.
对于我说的一些东西,你可能会说,我早就知道,保险公司会如此操作,但事实并非如此。
Here is what I'd say you should do.
这就是我说的你们必须做的
应用推荐