化简1-cos^4a-sin^4a/1-cos^6-sin^6acos^6应为cos^6a

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化简1-cos^4a-sin^4a/1-cos^6-sin^6acos^6应为cos^6a
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化简1-cos^4a-sin^4a/1-cos^6-sin^6acos^6应为cos^6a
化简1-cos^4a-sin^4a/1-cos^6-sin^6a
cos^6应为cos^6a

化简1-cos^4a-sin^4a/1-cos^6-sin^6acos^6应为cos^6a
1-cos^6-sin^6a=1-(sin^2+cos^a)(cos^4a-cos^2asin^2a+sin^4a)=1-cos^4a+cos^2asin^2a-sin^2a
=3cos^2asin^2a
1-cos^4a-sin^4a=cos^2a-cos^4a+sin^2a-cos^4a=2cos^2asin^a
原式=2/3

首先。题大概有点问题
1> (1-cos^4a-sin^4a)/(1-cos^6-sin^6a)
没打括号。 不然sin^4a/1 是怎么回事?
2> 1-cos^6 后面是不是少了个a? 1-cos^6a
cos^4a 是cos的4次方么?