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JEE Mains · Maths · STD 12 - 10. vector algebra

Let \(\hat{a}\) and \(\hat{b}\) be two unit vectors such that \(|(\hat{ a }+\hat{ b })+2(\hat{ a } \times \hat{ b })|=2\). If \(\theta \in(0, \pi)\) is the angle between \(\hat{a}\) અને \(\hat{b}\), then among the statements : \(( S_{1})\): \(2|\hat{ a } \times \hat{ b }|=|\hat{ a }-\hat{ b }|\) \((S_{2})\) : The projection of \(\hat{a}\) on \((\hat{a}+\hat{b})\) is \(\frac{1}{2}\)

  1. A Only \((S_{1})\) is true
  2. B Only \((S_{2})\) is true
  3. C Both \((S_{1})\) and \((S_{2})\) are true
  4. D Both \((S_{1})\) and \((S_{2})\) are false
Verified Solution

Answer & Solution

Correct Answer

(C) Both \((S_{1})\) and \((S_{2})\) are true

Step-by-step Solution

Detailed explanation

\(|(\hat{a}+\hat{b})+2(\hat{a} \times \hat{b})|=2, \theta \in(0, \pi)\) \(((\hat{a}+\hat{b})+2(\hat{a} \times \hat{b})) \cdot((\hat{a}+\hat{b})+2(\hat{a} \times \hat{b}))=4\) \(|\hat{a}+\hat{b}|^{2}+4|(\hat{a} \times \hat{b})|^{2}+0=4\) Let the angle be \(\theta\) between…