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The position vectors of the vertices A, B and C of a triangle are , k ˆ 3 j ˆ 3 i ˆ 2 + − , k ˆ 3 j ˆ 2 i ˆ 2 + + and , k ˆ 3 j ˆ i ˆ + + − respectively. Let l denotes the length of the angle bisector AD of ∠ BAC where D is on the line segment BC, the 2 l 2 equals:

1. 42
2. 50
3. 45
4. 49

Correct answer: 45

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