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MHT CET · Maths · Vector Algebra

Let \(\bar{a}, \overline{\mathrm{~b}}, \overline{\mathrm{c}}, \overline{\mathrm{d}}\) are vectors such that \(\bar{a} \times \overline{\mathrm{b}}=2 \hat{i}+3 \hat{\mathrm{j}}-\hat{\mathrm{k}}\) and \(\overline{\mathrm{c}} \times \overline{\mathrm{d}}=3 \hat{i}+2 \hat{\mathrm{j}}+\lambda \hat{\mathrm{k}}\) and if \(\left|\begin{array}{cc}\bar{a} \cdot \overline{\mathrm{c}} & \overline{\mathrm{b}} \cdot \overline{\mathrm{c}} \\ \bar{a} \cdot \overline{\mathrm{~d}} & \overline{\mathrm{~b}} \cdot \overline{\mathrm{~d}}\end{array}\right|=0\), then \(\lambda=\)

  1. A \(6\)
  2. B \(-6\)
  3. C \(12\)
  4. D \(-12\)
Verified Solution

Answer & Solution

Correct Answer

(C) \(12\)

Step-by-step Solution

Detailed explanation

\( \left|\begin{array}{ll} \bar{a} \cdot \overline{\mathrm{c}} & \overline{\mathrm{b}} \cdot \overline{\mathrm{c}} \\ \bar{a} \cdot \overline{\mathrm{d}} & \overline{\mathrm{b}} \cdot \overline{\mathrm{d}}\end{array}\right| = (\bar{a} \times \overline{\mathrm{b}}) \cdot (\overline{\mathrm{c}} \times \overline{\mathrm{d}}) \) \( (2 \hat{i}+3 \hat{j}-\hat{k}) \cdot (3 \hat{i}+2 \hat{j}+\lambda \hat{k}) = 0 \)