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CUET · MATHS · PYQ PAPER 2025

Let \(\vec{a}=\hat{i}+2 \hat{j}+3 \hat{k}\) and \(\vec{b}=-2 \hat{i}+3 \hat{j}-4 \hat{k}\), then which of the following statements are correct?
(A) \(|\vec{a}|=\sqrt{14}\)
(B) \(|\vec{b}|=29\)
(C) \(\vec{a} \cdot \vec{b}=8\)
(D) Angle between \(\vec{a}\) and \(\vec{b}\) is \(\cos ^{-1}\left(\frac{-8}{\sqrt{406}}\right)\)
Choose the correct answert from the option given below :

  1. A (A) and (D) only
  2. B (A) and (C) only
  3. C (B), (C) and (D) only
  4. D (A), (C) and (D) only
Verified Solution

Answer & Solution

Correct Answer

(A) (A) and (D) only

Step-by-step Solution

Detailed explanation

\(|\vec{a}| = \sqrt{1^2 + 2^2 + 3^2} = \sqrt{1+4+9} = \sqrt{14}\) \(|\vec{b}| = \sqrt{(-2)^2 + 3^2 + (-4)^2} = \sqrt{4+9+16} = \sqrt{29}\) \(\vec{a} \cdot \vec{b} = (1)(-2) + (2)(3) + (3)(-4) = -2 + 6 - 12 = -8\)…
From CUET
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