f(x)=(2sinx/2cosx/2)/(2sinx/2cosx/2+2sinx/2)
=(2sinx/2cosx/2)/[2sinx/2(cosx/2+1)]
=(cosx/2)/(cosx/2+1)
=1/(1+1/cosx/2)
f(x)=f(-x)
T=4π
f(x)=(2sinx/2cosx/2)/(2sinx/2cosx/2+2sinx/2)
=(2sinx/2cosx/2)/[2sinx/2(cosx/2+1)]
=(cosx/2)/(cosx/2+1)
=1/(1+1/cosx/2)
f(x)=f(-x)
T=4π