求锐角a!2sin²a+3sina-2=0

问题描述:

求锐角a!2sin²a+3sina-2=0
1求锐角a:2sin²a+3sina-2=0
2已知△ABC是锐角三角形,证明:(1)S△ABC=(1/2)absinC ,(2)a/sinA=b/sinB=c/sinC

1 sina=t
则化简为2t^2+3t-2=0
所以(2t-1)(t+2)=0
因为|t|