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NDA 2010
Exam
NDA
Year
2010
Subject
Mathematics
Chapter
Vector Algebra

NDA 2010 · Mathematics · Vector Algebra

Let a and b be two unit vectors and α be the angle between them. If...

Let a⃗\vec{a} and b⃗\vec{b} be two unit vectors and α\alpha be the angle between them. If (a⃗+b⃗)(\vec{a}+\vec{b}) is also the unit vector, then what is the value of α\alpha ?

Options

  1. Aπ4\frac{\pi}{4}
  2. Bπ3\frac{\pi}{3}
  3. C2π3\frac{2 \pi}{3}
  4. Dπ2\frac{\pi}{2}

Correct answer

A. π4\frac{\pi}{4}

Step-by-step solution

The correct answer is option (A).
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