设函数ƒ(x)=sin(x-17π/2),则对于任意的x∈R,ƒ(x)恒等于().

设函数ƒ(x)=sin(x-17π/2),则对于任意的x∈R,ƒ(x)恒等于().

A、sinx
B、cosx
C、-sinx
D、-cos
【正确答案】:D
【题目解析】:sin(x-17π/2)=sin[x-(8π+π/2)]=sinx cos(8π+π/2)-cosx sin(8π+π/2)=0-cosx=-cosx