已知sin(π/4+α)=2/3,则cos(π/4-α)的值等于多少?
问题描述:
已知sin(π/4+α)=2/3,则cos(π/4-α)的值等于多少?
答
sin(π/4+α)=2/3
cos(π/4-α)=sin[π/2-(π/4-a)]=sin(π/4+a)=2/3