题目内容
如图,正四棱柱ABCD—A1B1C1D1中,AA1=2AB,则异面直线A1B与AD1所成角的余弦值为![]()
A.
B.
C.
D.![]()
答案:D 连结BC1,则A1B与BC1所成角即为所求.在△A1BC1中,设AB=a,
则A1B=BC1=
a,A1C1=
a,∴cos∠A1BC1=
=
.
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题目内容
如图,正四棱柱ABCD—A1B1C1D1中,AA1=2AB,则异面直线A1B与AD1所成角的余弦值为![]()
A.
B.
C.
D.![]()
答案:D 连结BC1,则A1B与BC1所成角即为所求.在△A1BC1中,设AB=a,
则A1B=BC1=
a,A1C1=
a,∴cos∠A1BC1=
=
.