π |
3 |
e1 |
e2 |
e1 |
e2 |
e1 |
e2 |
CD |
e1 |
e2 |
GH |
e1 |
1 |
2 |
OA |
e2 |
OB |
OC |
e1 |
OD |
e2 |
CD |
OD |
OC |
e1 |
e2 |
OG |
e1 |
OH |
e2 |
GH |
OH |
OG |
e1 |
e2 |
GH |
e1 |
e2 |
GH |
[(2t-2)
|
(2t-2)2+(2t+1)2+2(2t-2)(2t+1)×
|
12t2-6t+3 |
-6 |
2×12 |
1 |
4 |
3 |
2 |
1 |
4 |
a |
i |
j |
b |
i |
j |
a |
b |
a |
b |
A.-2 | B.2 | C.-
| D.不存在 |
A.
| ||||||||
B.
| ||||||||
C.
| ||||||||
D.平面ABC的一个法向量是(1,-2,5) |
OA |
a |
OB |
b |
OC |
c |
OD |
d |
A.
| B.
| C.
| D.
|
AB |
AC |
BC |
AB |
BC |
CA |
0 |
AB |
AC |
AB |
AC |
AC |
AB |
A.①② | B.①④ | C.②③ | D.②③④ |
A.若a∥b,则a与b的方向相同或相反 |
B.若a∥b,b∥c,则a∥c |
C.若两个单位向量互相平行,则这两个单位向量相等 |
D.若a=b,b=c,则a=c |
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