化简:2cos4X+1/2×sin22X-cos2X 

问题描述:

化简:2cos4X+1/2×sin22X-cos2X
 

2cos4X+1/2×sin22X-cos2X
=2*[2(cos2x)^2-1]+1/2*(sin2x)^2-cos2x
=4(cos2x)^2-2+1/2*[1-(cos2x)^2]-cos2x
=7(cos2x)^2/2-cos2x-3/2