求锐角a!2sin²a+3sina-2=01求锐角a:2sin²a+3sina-2=02已知△ABC是锐角三角形,证明：（1）S△ABC=（1/2）absinC ,(2)a/sinA=b/sinB=c/sinC

求锐角a!2sin²a+3sina-2=01求锐角a:2sin²a+3sina-2=02已知△ABC是锐角三角形,证明：（1）S△ABC=（1/2）absinC ,(2)a/sinA=b/sinB=c/sinC
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

求锐角a!2sin²a+3sina-2=01求锐角a:2sin²a+3sina-2=02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|