14.长方体ABCD-A1B1C1D1中,E、F分别为线段AA1、B1C上的点,若AB=6,BC=5.AA1=3.则三棱锥D1-EDF的体积为( )
A. | $\frac{15}{2}$ | B. | 15 | ||
C. | 30 | D. | 随点E、F的改变而改变的值 |
10.如图四边形ABCD,AB=BD=DA=2.BC=CD=$\sqrt{2}$,现将△ABD沿BD折起,使二面角A-BD-C的大小在[$\frac{π}{6}$,$\frac{5π}{6}$],则直线AB与CD所成角的余弦值取值范围是( )
A. | [0,$\frac{\sqrt{2}}{8}$]∪($\frac{5\sqrt{2}}{8}$,1) | B. | [$\frac{\sqrt{2}}{8}$,$\frac{5\sqrt{2}}{8}$] | C. | [0,$\frac{\sqrt{2}}{8}$] | D. | [0,$\frac{5\sqrt{2}}{8}$] |
5.设奇函数f(x)满足f(x)=$\left\{\begin{array}{l}{-1(x≥1)}\\{1(0<x<1)}\end{array}\right.$,则f[f(sin6)]=( )
0 252799 252807 252813 252817 252823 252825 252829 252835 252837 252843 252849 252853 252855 252859 252865 252867 252873 252877 252879 252883 252885 252889 252891 252893 252894 252895 252897 252898 252899 252901 252903 252907 252909 252913 252915 252919 252925 252927 252933 252937 252939 252943 252949 252955 252957 252963 252967 252969 252975 252979 252985 252993 266669
A. | -1 | B. | 0 | C. | 1 | D. | 2 |