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CUET · MATHS · PYQ PAPER 2023

If \(\vec{a}=\hat{i}+2 \hat{j}+2 \hat{k},|\vec{b}|=5\) and the angle between \(\vec{a}\) and \(\vec{b}\) is \(\frac{\pi}{6}\), then the area of the triangle formed by these two vectors as two sides is :

  1. A \(\frac{15}{2}\) sq. unit
  2. B \(\frac{15 \sqrt{3}}{2}\) sq. unit
  3. C \(\frac{15}{4}\) sq. unit
  4. D \(15 \sqrt{3}\) sq. unit
Verified Solution

Answer & Solution

Correct Answer

(C) \(\frac{15}{4}\) sq. unit

Step-by-step Solution

Detailed explanation

\(|\vec{a}| = \sqrt{1^2+2^2+2^2} = \sqrt{1+4+4} = \sqrt{9} = 3\) Area \( = \frac{1}{2} |\vec{a}| |\vec{b}| \sin\theta \) Area \( = \frac{1}{2} (3)(5) \sin(\frac{\pi}{6}) \) Area \( = \frac{1}{2} (15) (\frac{1}{2}) = \frac{15}{4} \) sq. unit
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