a²tanB=b²tanA根据正弦定理a=2RsinA,b=2RsinB∴sin²A*sinB/cosB=sin²B*sinA/cosA∵sinA≠0,sinB≠0∴sinA/cosB=sinB/cosA∴sinAcosA=sinBcosB∴sin2A=sin2B∴2A=2B或2A+2B=180º∴A=B或a+B=...