cos^6+sin^6怎么算

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cos^6+sin^6怎么算

cos^6+sin^6怎么算
cos^6+sin^6怎么算

cos^6+sin^6怎么算
原式=cosx^6+sinx^6
=(cosx^3+sinx^3)²-2sin³x*cos³
=(cosx+sinx)²·(cos²x-cosx*sinx+sin²x)²-(2sinx*cosx)³/4
=(1+2sinx*cosx)*[1-(1/2)*sin2x]²-(1/4)*sin³2x
=(1+sin2x)*(1-sin2x+(1/4)*sin²2x)-(1/4)*sin³2x
=[1-sin2x+(1/4)*sin²2x]+[sin2x-sin²2x+(1/4)*sin³2x]-(1/4)*sin³2x
=1+(-sin2x+sin2x)+[(1/4)*sin²2x-sin²2x]+[(1/4)*sin³2x-(1/4)*sin³2x]
=1-(3/4)*sin²2x
=(3/4)*cos²2x

不能算!你看看少东西了吗?有角吗?