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3-1.Vectors
medium
The position vectors of points $A, B, C$ and $D$ are $A = 3\hat i + 4\hat j + 5\hat k,\,\,B = 4\hat i + 5\hat j + 6\hat k,\,\,C = 7\hat i + 9\hat j + 3\hat k$ and $D = 4\hat i + 6\hat j$ then the displacement vectors $AB$ and $CD $ are
A
Perpendicular
B
Antiparallel
C
Parallel
D
Inclined at an angle of $60^°$
Solution
(d) $\overrightarrow {AB} = (4\hat i + 5\hat j + 6\hat k) – (3\hat i + 4\hat j + 5\hat k)$=$\hat i + \hat j + \hat k$
$\overrightarrow {CD} = (4\hat i + 6\hat j) – (7\hat i + 9\hat j + 3\hat k)$$ = – 3\hat i – 3\hat j – 3\hat k$
$\overrightarrow {AB} $ and $\overrightarrow {CD} $ are anti parallel
Standard 11
Physics
