f(x)= (1+根号3*tanx)*cosx 的最小正周期

问题描述:

f(x)= (1+根号3*tanx)*cosx 的最小正周期

f(x)=(1+(根号3)tanx)cosx
=cosx+根号3tanx*cosx
=cosx+根号3sinx
=2(cosxcos60°+sinxsin60°)
=2cos(x-π/3)
因为cosx周期为2π,所以该函数最小正周期为2π

原式=2sin(x+30'),最小正周期为2派

f(x)=(1+√3tanx)cosx
=cosx+√3tanxcosx
=cosx+√3sinx
=2[(1/2)cosx+(√3/2)sinx]
=2[sin(π/6)cosx+cos(π/6)sinx]
=2sin(x+π/6)
T=2π

f(x)=cosx+√3tanxcosx
=cosx+√3(sinx/cosx)cosx
=√3sinx+cosx
=√[(√3)²+1²]sin(x+z)
=2sin(x+z)
其中tanz=1/√3
所以T=2π/1=2π