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CUET · MATHS · PYQ PAPER 2025

If \(\vec{a}, \vec{b}\) and \(\sqrt{3} \vec{a}+\vec{b}\) are unit vectors, then the angle between \(\vec{a}\) and \(\vec{b}\) is:

  1. A \(\frac{\pi}{2}\)
  2. B \(\frac{\pi}{3}\)
  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

\(( \sqrt{3}\vec{a}+\vec{b} ) \cdot ( \sqrt{3}\vec{a}+\vec{b} ) = 1^2\) \(3|\vec{a}|^2 + |\vec{b}|^2 + 2\sqrt{3}(\vec{a}\cdot\vec{b}) = 1\) \(3(1)^2 + (1)^2 + 2\sqrt{3}(|\vec{a}||\vec{b}|\cos\theta) = 1\) \(3 + 1 + 2\sqrt{3}(1)(1)\cos\theta = 1\) \(4 + 2\sqrt{3}\cos\theta = 1\)…
From CUET
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