猴捂脸一人猴捂脸一马猜一成语

一道简单的比例题……
虽然很简单,但是我就是不会做……
【捂脸】太丢人了……
麻烦好心的大哥哥大姐姐们帮帮我吧,小的在这里鞠躬啦~……
已知：a:b:c=2:3:4,ax=by=cz≠0
求：x:y:z
那个啥……

高一三角函数
sinx+acosx≤根号下1+a^2
如何推导？ 在线等，急~
捂脸……acosx＋bsinx＝根号(a^2+b^2)sin[x+arctan(a/b)] 怎么得出来的？是个公式吗？

帮帮忙把下面这篇短文纠一下错.本人文笔不好（捂脸）,多多包涵.
My life has changed a lot in the last few years.My daily life is different things when I was a child.For example,I used to like tests because the tests were easy that I needn’t review.Now,the math tests become more and more difficult,I must review it,or I can’t get good grades.And my math teacher often says I’m not careful enough.I don’t like tests but I don’t mind them now.
I used to hate English classes.Now it’s my favorite.Because I had met a good teacher since ten years.But I can’t find him now,I just want to say “Thanks” to him,but it may can’t become true.Maybe I won’t meet him forever.
I used to like skating when I was young,but now,I enioy playing badminton.I have badminton classes every weekend and I often have competitions with my cousin.Both he and I like playing badminton.He is stronger than me and I am faster than him,so we can’t beat each other.
I used to walk to school.Now I ride my bicycle to school,walk back home in the morning ,walk to school again in the afternoon ,ride my bicycle to home in the evening.That seems boring,but I usually find something interesting on the way to school.