答案是1吧
令x=arctana y=arctanb 所以tanx=a tany=b
代到前面 (tanx+1)(tany+1)=2
化简 tanxtany +tanx+tany +1 =2
tanx+tany/(1-tanxtany)=1
tan(x+y)=tanx+tany/(1-tanxtany)=1
arctana+arctanb=x+y=arctan(x+y)=1
答案是1吧
令x=arctana y=arctanb 所以tanx=a tany=b
代到前面 (tanx+1)(tany+1)=2
化简 tanxtany +tanx+tany +1 =2
tanx+tany/(1-tanxtany)=1
tan(x+y)=tanx+tany/(1-tanxtany)=1
arctana+arctanb=x+y=arctan(x+y)=1