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AP EAMCET · Maths · Vector Algebra

If \(\bar{a}, \bar{b}, \bar{c}\) are three unit vectors such that \(\bar{a} \times(\bar{b} \times \bar{c})=\frac{\sqrt{3}}{2} \bar{b}+\frac{\bar{c}}{2}\) and \(\alpha, \beta\) are the angles between \(\overline{\mathrm{a}}, \overline{\mathrm{c}}\) and \(\overline{\mathrm{a}}, \overline{\mathrm{b}}\) respectively, then \(\alpha+\beta=\)

  1. A \(\frac{\pi}{2}\)
  2. B \(\frac{7 \pi}{6}\)
  3. C \(\frac{\pi}{6}\)
  4. D \(\frac{5 \pi}{6}\)
Verified Solution

Answer & Solution

Correct Answer

(D) \(\frac{5 \pi}{6}\)

Step-by-step Solution

Detailed explanation

\(\bar{a} \times (\bar{b} \times \bar{c}) = (\bar{a} \cdot \bar{c}) \bar{b} - (\bar{a} \cdot \bar{b}) \bar{c}\) \(\bar{a} \cdot \bar{c} = |\bar{a}||\bar{c}|\cos\alpha = \cos\alpha\) \(\bar{a} \cdot \bar{b} = |\bar{a}||\bar{b}|\cos\beta = \cos\beta\)…