tanA-tanB/tanA+tanB=sin(A-B)/sin(A+B) 请问是怎么证明的,谢谢!

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tanA-tanB/tanA+tanB=sin(A-B)/sin(A+B) 请问是怎么证明的,谢谢!
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tanA-tanB/tanA+tanB=sin(A-B)/sin(A+B) 请问是怎么证明的,谢谢!
tanA-tanB/tanA+tanB=sin(A-B)/sin(A+B) 请问是怎么证明的,谢谢!

tanA-tanB/tanA+tanB=sin(A-B)/sin(A+B) 请问是怎么证明的,谢谢!

tanA-tanB/tanA+tanB
=sinA/cosA-sinB/cosB / sinA/cosA + sinB/cosB 分子分母分别乘cosAcosB
=sinAcosB-sinBcosA /sinAcosB+sinBcosA
=sin(A-B)/sin(A+B)