(2012)设a(x)=1-cosx，β(x)=2x，则当x→0时，下列结论中正确的是：A.a(x)与β(x)是等价无穷小B.a(x)与β(x)是高价

1.[](2012)设a(x)=1-cosx，β(x)=2x，则当x→0时，下列结论中正确的是：A.a(x)与β(x)是等价无穷小 B.a(x)与β(x)是高价无穷小 C.a(x)是β(x)的低阶无穷小 D.a(x)与β(x)是同阶无穷小但不是等价无穷小ABCD