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AP EAMCET · Maths · Vector Algebra

\(\vec{u}, \vec{v}, \vec{w}\) are three unit vectors. Let \(\vec{p}=\vec{u}+\vec{v}+\vec{w}, \vec{q}\) \(=\vec{u} \times(\vec{v} \times \vec{w})\).If \(\vec{p} \cdot \vec{u}=\frac{3}{2}, \vec{p} \cdot \vec{v}=\frac{7}{4},|\vec{p}|=2\) and \(\vec{v}=\mathrm{K} \vec{q}\), then \(K=\)

  1. A \(-1\)
  2. B \(2\)
  3. C \(3\)
  4. D \(-2\)
Verified Solution

Answer & Solution

Correct Answer

(B) \(2\)

Step-by-step Solution

Detailed explanation

Given that \(|\vec{u}|=|\vec{v}|=|\vec{w}|=1\) \(\therefore \vec{p} \cdot \vec{u}=(\vec{u}+\vec{v}+\vec{w}) \cdot \vec{u}=\frac{3}{2} \Rightarrow|\vec{u}|^2+\vec{u} \cdot \vec{v}+\vec{w} \cdot \vec{u}=\frac{3}{2}\)…