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?

sin(π/4+α)=2/3
cos(π/4-α)=sin[π/2-(π/4-a)]=sin(π/4+a)=2/3