sin(a+b)=1/2,sin(a-b)=1/3,则tana*cotb=?还有道tana=2,求sin^2a-sinacosa-cos^2a=
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sin(a+b)=1/2,sin(a-b)=1/3,则tana*cotb=?还有道tana=2,求sin^2a-sinacosa-cos^2a=
sin(a+b)=1/2,sin(a-b)=1/3,则tana*cotb=?
还有道tana=2,求sin^2a-sinacosa-cos^2a=
sin(a+b)=1/2,sin(a-b)=1/3,则tana*cotb=?还有道tana=2,求sin^2a-sinacosa-cos^2a=
sin(a+b)=1/2
sinacosb+cosasinb=1/2 ---------------[1]
sin(a-b)=1/3
sinacosb-cosasinb=1/3 --------------[2]
[1]+[2]=sinacosb=5/12
[1]-[2]=cosasinb=1/12
tana*cotb=(sina/cosa)*(cosb/sinb)=(sinacosb)/(cosasinb)=(5/12)/(1/12)=5
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