化简sin(π+α)cos(2π−α)cos(π2+α)sin(π+α)cos(2π−α)cos(π2+α)所的的结果是( )。单项选择题选项:
A.sinαsinα B.−sinα−sinα C.cosαcosα D.−cosα−cosα正确答案D
化简sin(π+α)cos(2π−α)cos(π2+α)sin(π+α)cos(2π−α)cos(π2+α)所的的结果是( )。单项选择题选项:
A.sinαsinα B.−sinα−sinα C.cosαcosα D.−cosα−cosα正确答案D