题目内容
如图,△ABC中,
=2
,
=2
,设
=
,
=
,则
= .

| AE |
| EB |
| BD |
| DC |
| AB |
| a |
| AC |
| b |
| DE |
考点:向量加减混合运算及其几何意义
专题:平面向量及应用
分析:由∵△ABC中,
=2
,
=2
,利用向量加法的三角形法则和平行四边形法则,可得
=
+
=
+
=
(
-
)-
=
+
,进而得到答案.
| AE |
| EB |
| BD |
| DC |
| DE |
| DB |
| BE |
| 2 |
| 3 |
| CB |
| 1 |
| 3 |
| BA |
| 2 |
| 3 |
| AB |
| AC |
| 1 |
| 3 |
| AB |
| 1 |
| 3 |
| AB |
| 2 |
| 3 |
| AC |
解答:
解:∵△ABC中,
=2
,
=2
,
=
,
=
,
∴
=
+
=
+
=
(
-
)-
=
+
=
+
.

故答案为:
+
| AE |
| EB |
| BD |
| DC |
| AB |
| a |
| AC |
| b |
∴
| DE |
| DB |
| BE |
| 2 |
| 3 |
| CB |
| 1 |
| 3 |
| BA |
| 2 |
| 3 |
| AB |
| AC |
| 1 |
| 3 |
| AB |
| 1 |
| 3 |
| AB |
| 2 |
| 3 |
| AC |
| 1 |
| 3 |
| a |
| 2 |
| 3 |
| b |
故答案为:
| 1 |
| 3 |
| a |
| 2 |
| 3 |
| b |
点评:本题考查两个向量的加法和减法法则,以及共线向量的表示方法,体现了数形结合的数学思想.
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