花漂零
春芽
共回答了7个问题采纳率：85.7% 举报
tanB=1/4,tanC=3/5
tan(B+C)= ( tanB+tanC)/(1-tanA*tanB)
= [(1/4)+(3/5)] / [1-(1/4)*(3/5)]
= 1
tanA=-tan(B+C)=-1
A=135度
角A最大,所以a=√17,角B最小,b边最短
sinB=1/√5 sinA=√2/2
b=a/sinA*sinB
=√17/(√2/2)*(1/√5)
=√170 /5
1年前
追问
3
![]()
举报
花漂零
tanB=1/4 x=4t , y=1t , r=√5 t tanB=y/x sinB=y/r=1/√5
![]()
举报
花漂零
哦，你是对的 sinB=1/√17 b=a/sinA*sinB =√17/(√2/2)*(1/√17) =√2
赞
