△ABC中,sinC/2+sinC/2=根号2,abc成等比数列,求sinA
问题描述：
△ABC中,sinC/2+sinC/2=根号2,abc成等比数列,求sinA
sinC/2+cosC/2=根号2,对不起啊
答
sinC/2+cosC/2=√2,
sin(C/2+π/4)=1
C/2+π/4=π/2
C/2=π/4
C=π/2
abc
成等比数列
b²=ac
sin²B=sinA
1-sin²A=sinA
sin²A+sinA-1=0
sinA=(√5-1)/2