cos2(π/4+α)+cos2(π/4-α）= (2是平方）
问题描述：
cos2(π/4+α)+cos2(π/4-α）= (2是平方）
答
[cos(π/4+α)]^2+[cos(π/2-(π/4+α))]^2
=[cos(π/4+α)]^2+[sin(π/4+α)]^2
=1