Practicing Success

Target Exam

CUET

Subject

-- Mathematics - Section B1

Chapter

Vectors

Question:

If the area of a parallelogram whose diagonals coincide with the following pair of vectors is $5\sqrt{3}$, then vectors are

Options:

$3\hat i +2\hat j-\hat k, 3\hat i-\hat j + 4\hat k$

$\frac{3}{2}\hat i +\frac{1}{2}\hat j-\hat k, 2\hat i-6\hat j + 8\hat k$

$3\hat i +\hat j-2\hat k, \hat i+3\hat j + 4\hat k$

none of these

Correct Answer:

$\frac{3}{2}\hat i +\frac{1}{2}\hat j-\hat k, 2\hat i-6\hat j + 8\hat k$

Explanation:

If $\vec a, \vec b$ are diagonals of a parallelogram, then its area is $\frac{1}{2}|\vec a×\vec b|$

Clearly, $\frac{1}{2}|\vec a×\vec b|=5\sqrt{3}$ is satisfied by the pair of vectors given in option (2).