(1-sin^6a-cos^6a)/(sin^2a-sin^4a)

1个回答

  • 分子=1-sin^6a-cos^6a

    =1-(sin^6a+cos^6a)

    =1-(sin²a+cos²a)(sin^4 a-sin^acos6a+cos^4 a)

    =1-(sin^4 a-sin^acos^a+cos^4 a)

    =1-〔(sin²a+cos²a)²-3sin^acos^a〕

    =1-(1-3sin²acos²a)

    =3sin²acos²a

    分母=(sina+sin²a)(sina-sin²a)

    =sina(1+sina)sina(1-sina)

    =sin²a(1-sin²a)

    =3sin²acos²a

    分子/分母=(3sin²acos²a)/(sin²acos²a)=3