已知函数f(x)=(cos2xcosx+sin2xsinx)sinx,x∈R,则f(x)是( )
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∵f(x)=(cos2xcosx+sin2xsinx)sinx=cos2xcosxsinx+sin2xsin2x
=
sin2xcos2x+1 2 sin2x(1-cos2x) 2
=
+sin4x 4 sin2x-sin2xcos2x 2
=
sin2x1 2
由周期公式可得T=π,且f(-x)=
sin(-2x)=-1 2
sin2x,即函数f(x)为奇函数1 2
故选A
已知函数f(x)=(cos2xcosx+sin2xsinx)sinx,x∈R,则f(x)是( )
|
∵f(x)=(cos2xcosx+sin2xsinx)sinx=cos2xcosxsinx+sin2xsin2x
=
sin2xcos2x+1 2 sin2x(1-cos2x) 2
=
+sin4x 4 sin2x-sin2xcos2x 2
=
sin2x1 2
由周期公式可得T=π,且f(-x)=
sin(-2x)=-1 2
sin2x,即函数f(x)为奇函数1 2
故选A