sin(π-α)+cos(π/2+α)＝-m則cos(3π/2－α)+2sin(2π－α)＝（）A,-2m/3 B,2m/3 C,3m/2 D,-3m/2

熱心網(wǎng)友

題目寫錯(cuò)了，我替你改一下題目：sin(π+α)+cos(π/2+α)＝-m則cos(3π/2－α)+2sin(2π－α)＝（）因?yàn)閟in(π+α)+cos(π/2+α)=-sinα-sinα=-2sinα=-m所以sinα=m/2從而cos(3π/2－α)+2sin(2π－α)＝-sinα-2sinα=-3sinα=-3m/2選擇D。

熱心網(wǎng)友

又有問題吧sin(π-α)+cos(π/2+α)=sinα+sin[π/2-(π/2+α)]=sinα-sinα=0=-m要么ABCD都選，要么都不選

熱心網(wǎng)友

怎么感覺好象錯(cuò)了