y=1/2sin^2*2x怎么等于y=1/2*(1-cos4x)/2求详解步骤

y=1/2sin^2*2x怎么等于y=1/2*(1-cos4x)/2求详解步骤
y=1/2sin^2*2x怎么等于y=1/2*(1-cos4x)/2求详解步骤

y=1/2sin^2*2x怎么等于y=1/2*(1-cos4x)/2求详解步骤
cos2x=1-2sin²x
则cos4x=1-2sin²2x
所以sin²2x=(1-cos4x)/2