PrepRung
Sign inSign up free

NDA 2025 Maths · Mathematics · Vector Algebra · easy

The vector with initial point (1,2,3) and terminal point (3,5,9) has magnitude

Single correct option

The vector with initial point (1,2,3)(1,2,3) and terminal point (3,5,9)(3,5,9) has magnitude
  1. A. 55
  2. B. 77
  3. C. 66
  4. D. 94\sqrt{94}
Show answer and solution

Answer: (B) 77

The vector is (3−1)i^+(5−2)j^+(9−3)k^=2i^+3j^+6k^(3-1)\hat i+(5-2)\hat j+(9-3)\hat k=2\hat i+3\hat j+6\hat k, whose magnitude is 4+9+36=7\sqrt{4+9+36}=7. The value 55 ignores the third component, 66 is the largest component alone, and 94\sqrt{94} comes from adding the terminal point's coordinates (3,5,9)(3,5,9) and squaring instead of subtracting.
Report a mistake

Original question written in the NDA 2025 Maths pattern and checked twice for the correct answer. Not an official question paper. How we write and check questions · Corrections policy · Report a mistake