A:180
B:90
C:300
D:150
I think Lily should wear __________ more because she worries a lot and often gets stressed.
在△ABC中,若(a+b+c)(b+c﹣a)=3bc,且sinA=2sinBcosC,试确定三角形的形状.
林则徐、魏源向西方学习的思想,其目的是( )