![已知sin(a+b)=23,sin(a-b)=34,求[tan(a+b）-tana-tanb]tan²b*tan(a+b)的值,第1張](data:image/gif;base64,R0lGODlhAQABAAAAACH5BAEKAAEALAAAAAABAAEAAAICTAEAOw== "已知sin(a+b)=23,sin(a-b)=34,求[tan(a+b）-tana-tanb]tan²b*tan(a+b)的值,第1張")
已知sin(a b)=2/3,sin(a-b)=3/4,求[tan(a b）-tana-tanb]/tan²b*tan(a b)的值網友廻答：
- sin(a b)=sinacosb cosasinb=2/3……(1)
sin(a-b)=sinacosb-cosasinb=3/4……(2)
(1) (2)
2sinacosb=17/12,
sinacosb=17/24
(1)-(2)
2cosasinb=-1/12,
cosasinb=-1/24
tan(a b)-tana-tanb
=tan(a b)-(tana tanb)
=tan(a b)-[tan(a b)*(1-tanatanb]
=tana*tanb*tan(a b)
(tan(a b)-tana-tanb)/(tan^2b*tan(a b))
=tana*tanb*tan(a b)/(tan^2b*tan(a b))
=tana*tanb/tan^2b
=tana/tanb
=sinacosb/cosasinb
=(17/24)/(-1/24)
=-17
admin![已知sin(a+b)=23,sin(a-b)=34,求[tan(a+b）-tana-tanb]tan²b*tan(a+b)的值,第1張](/pic/已知sin(a+b)=23,sin(a-b)=34,求[tan(a+b）-tana-tanb]tan²b*tan(a+b)的值.jpg "已知sin(a+b)=23,sin(a-b)=34,求[tan(a+b）-tana-tanb]tan²b*tan(a+b)的值,第1張")
![已知sin(a+b)=23,sin(a-b)=34,求[tan(a+b）-tana-tanb]tan²b*tan(a+b)的值,第2張](/statics/default/images/niming.jpg "已知sin(a+b)=23,sin(a-b)=34,求[tan(a+b）-tana-tanb]tan²b*tan(a+b)的值,第2張")
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