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MHT CET · Maths · Vector Algebra

If the area of parallelogram, whose diagonals are \(\hat{i}-\hat{j}+2 \hat{k}\) and \(2 \hat{i}+3 \hat{j}+\alpha \hat{k}\) is \(\frac{\sqrt{93}}{2}\) sq. unit, then \(\alpha=\)

  1. A \(-4,2\)
  2. B \(-3,-2\)
  3. C 2,1
  4. D 4,2
Verified Solution

Answer & Solution

Correct Answer

(A) \(-4,2\)

Step-by-step Solution

Detailed explanation

Area \( = \frac{1}{2} | \vec{d_1} \times \vec{d_2} | \) \( \vec{d_1} \times \vec{d_2} = \begin{vmatrix} \hat{i} & \hat{j} & \hat{k} \\ 1 & -1 & 2 \\ 2 & 3 & \alpha \end{vmatrix} = \hat{i}(-\alpha-6) - \hat{j}(\alpha-4) + \hat{k}(3+2) = (-\alpha-6)\hat{i} + (4-\alpha)\hat{j} + 5\hat{k} \)