The angle between the two vectors A→ = 3î + 4ĵ

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The angle between the two vectors A^{^→} = 3î + 4ĵ + 5k̂ and B^{^→} = 3î + 4ĵ - 5k̂ will be

1. zero
2. 45°
3. 90°
4. 180°

Correct Option: C

A^{^→} = 3î + 4ĵ + 5k̂ , B^{^→} = 3î + 4ĵ - 5k̂
A^{^→} . B^{^→} = (3î + 4ĵ + 5k̂) . (3î + 4ĵ - 5k̂)
| A^{^→} | | B^{^→} | cosθ = 9 + 16 - 25 = 0
| A^{^→} | ≠ 0 , | B^{^→} | ≠ 0 , hence, cos θ = 0, θ = 90°