万能公式知道吧是要记的哦...sin2x=2tanx/(1+tan^2x)=4/5cos2x=(1-tan^2x)/(1+tan^2x)=-3/5原式=2sin^2x-1+1+sin2x/2-3(2cos^2x-1+1)/2=-cos2x+1+sin2x/2-3cos2x/2-3/2=-5cos2x/2+sin2x/2-1/2=3/2+2/5-1/2=7/5...