alleryVector r̄ is collinear with ā = î - 2ĵ + 2k̂ and |r̄| = 12. Find r̄:
A4î - 8ĵ + 8k̂
Bî - 2ĵ + 2k̂
C12î - 24ĵ + 24k̂
D4î + 8ĵ + 8k̂
Answer & Solution
Correct answer: A. 4î - 8ĵ + 8k̂
Unit vector in direction of ā: â = ā/|ā| = (î - 2ĵ + 2k̂)/√(1+4+4) = (1/3)(î - 2ĵ + 2k̂).
**Vector of magnitude 12:** r̄ = 12â = 4î - 8ĵ + 8k̂.
**Check:** |r̄| = √(16+64+64) = √144 = 12 ✓.
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