Which function is periodic with period π\piπ?
f(x)=sin(x)f(x) = \sin(x)f(x)=sin(x)
f(x)=sin(2x)f(x) = \sin(2x)f(x)=sin(2x)
f(x)=cos(x/2)f(x) = \cos(x/2)f(x)=cos(x/2)
f(x)=tan(x)f(x) = \tan(x)f(x)=tan(x)