sin^6a+cos^6a-2sin^4a-cos^4a+sin^2a=0我想知道,这道题为什么等于零,
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sin^6a+cos^6a-2sin^4a-cos^4a+sin^2a=0我想知道,这道题为什么等于零,
sin^6a+cos^6a-2sin^4a-cos^4a+sin^2a=0
我想知道,这道题为什么等于零,
sin^6a+cos^6a-2sin^4a-cos^4a+sin^2a=0我想知道,这道题为什么等于零,
原式左边=cos^4A*(cos^2A-1)+(sin^3A-sinA)^2
=-sin^2Acos^4A+sin^2A(sin^2A-1)^2
=-sin^2Acos^4A+sin^2A(-cos^2A)^2
=-sin^2Acos^4A+sin^2Acos^4A
=0
左边=(sin^2a+cos^2a)(sin^4a-sin^2acos^2a+cos^4a)-2sin^4a-cos^4a+sin^2a
=sin^4a-sin^2acos^2a+cos^4a-2sin^4a-cos^4a+sin^2a
=-sin^4a-sin^2acos^2a+sin^2a
=sin^2a(1-sin^2a)-sin^2acos^2a
=sin^2acos^2a-sin^2acos^2a
=0=右边
(1-sin^6a-cos^6a)/(sin^2a-sin^4a)
=1-(sin^6a+cos^6a) ------(1)=1-(sin^a+cos^a)(sin^4 a-sin^acos6a+cos^4 a) --------(2)由(1)怎么能到(2)呢=1-(sin^6a+cos^6a)=1-(sin^2a+cos^2a)(sin^4 a-sin^2acos^2a+cos^4a)
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已知(4sin a-2cos a)/(5cos a +3sin a)=6/11,求cos^4 a-sin^4 a
化简(1-sin^6 a-cos^6 a)/(cos^2 a-cos^4 a)==
(1-sin^6 a-cos^6 a)/(sin^2 a-sin^4 a)的化简结果,
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(1-sin^6a-cos^6a)/(1-sin^4a-cos^4a)=?
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sin^6a+cos^6a-2sin^4a-cos^4a+sin^2a=0我想知道,这道题为什么等于零,