MCQ
A unit vector in the $xy - $ plane which is perpendicular to $4i - 3j + k$ is
  • A
    $\frac{{i + j}}{{\sqrt 2 }}$
  • $\frac{1}{5}(3i + 4j)$
  • C
    $\frac{1}{5}\,(3i - 4j)$
  • D
    None of these

Answer

Correct option: B.
$\frac{1}{5}(3i + 4j)$
b
(b) ${x^2} + {y^2} = 1$

Let vector be $xi + yj,$ then $4x - 3y = 0$

$ \Rightarrow 4x = 3y \Rightarrow x = \frac{3}{5},\,\,y = \frac{4}{5},$

Hence the required vector is $\frac{1}{5}(3i + 4j).$

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