化简（cos^2α-sin^2α）/2cot(π/4+α)cos^2(π/4-α)
问题描述：
化简（cos^2α-sin^2α）/2cot(π/4+α)cos^2(π/4-α)
答
cos^2α-sin^2α=(cosα+sinα)(cosα-sinα)=cos2α2cot(π/4+α)=2tan(π/4-α)=2(1-tanα)/(1+tanα)cos^2(π/4-α)=[1+cos(π/2-2α)]/2=(1+sin2α)/2=(cosα+sinα)^2/22cot(π/4+α)cos^2(π/4-α)=(1-tanα)(...