A:C10H16N2O8
B:C10H20N2O8
C:C8H16N2O8
D:C16H20N2O8Cl
如图,正六边形ABCDEF的边长为2,则对角线AF=____.
如图,在▱ABCD中,点E是AD的中点,延长BC到点F,使CF:BC=1:2,连接DF,EC.若AB=5,AD=8,sinB=45,则DF的长等于( )