化简：(4cos^4a-4cos^2+1)/[2tan(π/4-a)sin^2(π/4+a)]
问题描述：
化简：(4cos^4a-4cos^2+1)/[2tan(π/4-a)sin^2(π/4+a)]
答
=(2cos2a-1)2=[2tan(π/4-a)*cos2(π/4-a)]
=cos22a/[2sin(π/4-a)cos(π/4-a)]
=cos22a/sin(π/2-2a)
=cos22a/cos2a
=cos2a