Question
Let a , b , ( a b ) be unit vectors. What is ( a b ) equal to?
NDA
Mathematics
Vector Algebra
2025
NDA 2025 (Phase 1)
NDA Mathematics Question (2025) — Solution
Options
- A. 0
- B. 1 2
- C. 1
- D. 3
Answer
A. 0
Step-by-step solution
Given | a | = 1, | b | = 1, and | a b | = 1. Using Lagrange's identity, | a b |^2 + ( a b )^2 = | a |^2 | b |^2. Substituting the given values, 1^2 + ( a b )^2 = 1^2 1^2. 1 + ( a b )^2 = 1. ( a b )^2 = 0 a b = 0. Answer: 0
Related: Mathematics — Vector Algebra · All PYQ Banks