Question

Vector A^→ = + i˄ + j˄ – 2k˄ and vector B^➙ = 2i˄ – j˄ + k˄ Find the unit vector in direction of A^➙ × B^➙

(A) [1 / √(23)] (– i˄ – 5j˄ – 2k˄)

(B) [1 / √(35)] (– i˄ – 5j˄ – 3k˄) 

(C) [1 / √(29)] (– i˄ – 5j˄ – 3k˄) 

(D) [1 / √(35)] (– i˄ – 5j˄ – 3k˄)

Answer 1

Correct option: (D) [1 / √(35)] (– i˄ – 5j˄ – 3k˄)

Explanation:

= i^˄(1 – 2) – j^˄(1 + 4) + k^˄(– 1 – 2)

= – i^˄ – 5j^˄ – 3k^˄

unit vector = {(A^➙ × B^➙) / (|A^➙ × B^➙|)} = {(– i˄ – 5j˄ – 3k˄) / (1² + 5² + 3²)}

= {(– i˄ – 5j˄ – 3k˄) / (√35)}