(1)已知0<x<π/2,cosx=4/5,則tanx=(2)函數y= cos(3π/2 -x)/cos(3π-x)最小正週期是

(1)已知0<x<π/2,cosx=4/5,則tanx=(2)函數y= cos(3π/2 -x)/cos(3π-x)最小正週期是

(1)cosx=4/5,sinx=3/5則tanx=3/5/4/5=3/4(2)cos(3π/2 -x)=cos(x+π/2)=-sinx cos(3π-x)=-cosx y= cos(3π/2 -x)/cos(3π-x)=tanx所以最小正週期π