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CUET · MATHS · PYQ PAPER 2025

If \(\theta\) is an acute angle and the vector \(\vec{a}=(\sin \theta) \hat{i}+(\cos \theta) \hat{j}\) is perpendicular to the vector \(\vec{b}=\hat{i}-\sqrt{3} \hat{j}\) then \(\theta\) is equal to:

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

Answer & Solution

Correct Answer

(B) \(\frac{\pi}{3}\)

Step-by-step Solution

Detailed explanation

\(\vec{a} \cdot \vec{b} = 0\) \((\sin \theta)(1) + (\cos \theta)(-\sqrt{3}) = 0\) \(\sin \theta = \sqrt{3} \cos \theta\) \(\tan \theta = \sqrt{3}\) \(\theta = \frac{\pi}{3}\)
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