您应该是打漏了一个3题目应该是 已知3sin(b)=sin(2a+b),求证tan(a+b)=2tan(a)3sinB=sin（2A+B）3sinB=sinAcos(A+B)+cosAsin(A+B)3sinB=sinA(cosAcosB-sinAsinB)+cosA(sinAcosB+cosAsinB)3sinB=sinAcosAcosB-sinAsinA...