3(sinA)^2+2(sinB)^2=1,3sin2B-2sin2B=0,求A+2B

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3(sinA)^2+2(sinB)^2=1,3sin2B-2sin2B=0,求A+2B3(sinA)^2+2(sinB)^2=1,3sin2B-2sin2B=0,求A+2B3(sinA)^2+2(si

3(sinA)^2+2(sinB)^2=1,3sin2B-2sin2B=0,求A+2B
3(sinA)^2+2(sinB)^2=1,3sin2B-2sin2B=0,求A+2B

3(sinA)^2+2(sinB)^2=1,3sin2B-2sin2B=0,求A+2B
3sin^2(A)=1-2sin^2(B)=cos2B>0
3sin2B-2sin2B=sin2B=0 2B=π
∴cos2B=1
3sin^2(A)=1
sinA=√3/3
A=arcsin(√3/3)
A+2B=arcsin(√3/3)+π