已知sin(2a-b)=3sinb,則tan(a-b)/tana 網友廻答:
- sin(2a-b)=3sinb
sin[(a-b) a]=3sin[a-(a-b)]
sin(a-b)cosa cos(a-b)sina=3[sinacos(a-b)-cosasin(a-b)]
sin(a-b)cosa cos(a-b)sina=3sinacos(a-b)-3cosasin(a-b)
4sin(a-b)cosa=2sinacos(a-b)
2sin(a-b)cosa=sinacos(a-b)
2sin(a-b)/cos(a-b)=sina/cosa
2tan(a-b)=tana
tan(a-b)/tana=1/2
網友廻答:
- sin(2a-b)=3sinb
sin[a (a-b)]=3sin[a-(a-b)]
sinacos(a-b) cosasin(a-b)=3sinacos(a-b)-3cosasin(a-b)
4cosasin(a-b)=2sinacos(a-b)
[cosasin(a-b)]/[sinacos(a-b)]=1/2
tan(a-b)/tana=1/2
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