已知3sinB=sin(2A+B),求证tan(A+B)=2tanA

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已知3sinB=sin(2A+B),求证tan(A+B)=2tanA已知3sinB=sin(2A+B),求证tan(A+B)=2tanA已知3sinB=sin(2A+B),求证tan(A+B)=2ta

已知3sinB=sin(2A+B),求证tan(A+B)=2tanA
已知3sinB=sin(2A+B),求证tan(A+B)=2tanA

已知3sinB=sin(2A+B),求证tan(A+B)=2tanA
3sinB=sin(2A+B)
3sin(A+B-A)=sin(A+B+A)
3sin(A+B)cosA-3cos(A+B)sinA=sin(A+B)cosA+sinAcos(A+B)
2sin(A+B)cosA=4cos(A+B)sinA
tan(A+B)=2tanA