举报
Linger25
cos^2x(2cos^2x+3)-sin^2x(2cos^2x+3)-4sin^2xcos^2x+3 =2cos^4x+3cos^2x-2cos^2xsin^2x-3sin^2x-4sin^2xcos^2x+3 =2cos^4x+3cos^2x-6cos^2xsin^2x-3sin^2x+3 =2cos^4x+3cos^2x-6cos^2x(1-cos^2x)-3(1-cos^2x)+3 =2cos^4x+3cos^2x-6cos^2x+6cos^4x-3+3cos^2x+3 =8cos^4x
