A
anh_thunder


[TEX]\\a\\A=2cos^4x-sin^4x+sin^2x.cos^2x+3sin^2x\\\\\\b\\B=3(sin^8x-cos^8x)+4(cos^6x-2sin^6x)+6sin^4x\\c\\\C=\frac{cos^2x-sin^2x}{cot^2x-tan^2x}=sin^2xcos^2x[/TEX]
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