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