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MHT CET · Maths · Vector Algebra

If \(\bar{a}, \bar{b}, \bar{c}\) are three coplanar vectors such that \(|\bar{a}|=1,|\bar{b}|=2\), \(\overline{\mathrm{b}} \cdot \overline{\mathrm{c}}=8\), the angle between \(\overline{\mathrm{b}}\) and \(\overline{\mathrm{c}}\) is \(45^{\circ}\), then \(|\bar{a} \times(\bar{b} \times \bar{c})|=\)

  1. A 8
  2. B \(4 \sqrt{2}\)
  3. C \(\sqrt{2}\)
  4. D \(8 \sqrt{2}\)
Verified Solution

Answer & Solution

Correct Answer

(A) 8

Step-by-step Solution

Detailed explanation

\(\overline{\mathrm{b}} \cdot \overline{\mathrm{c}}=|\bar{b}||\bar{c}| \cos 45^{\circ} \Rightarrow 8=2 \cdot |\bar{c}| \cdot \frac{1}{\sqrt{2}} \Rightarrow |\bar{c}|=4 \sqrt{2}\) \(|\bar{b} \times \bar{c}|=|\bar{b}||\bar{c}| \sin 45^{\circ} = 2 \cdot 4 \sqrt{2} \cdot \frac{1}{\sqrt{2}} = 8\)