JEE Main202330 Jan 2023Morning ShiftMathematicsVector AlgebraActual
If a → , b → , c → are three non-zero vectors and n ^ is a unit vector perpendicular to c → such that a → = α b → - n ^ , α ≠ 0 and b → · c → = 12 , then c → × a → × b → is equal to:
Options
- A15
- B9
- C12
- D6
Correct answer
C. 12
Step-by-step solution
Given: a → = α b → - n ^ where, α ≠ 0 ⇒ a → · c → = α b → · c → - n ^ · c → ⇒ a → · c → = 12 α - 0 Since, n ^ ⊥ c → ⇒ n ^ · c → = 0 . Now, c → × a → × b → = c → · b → a → - c → · a → b → ⇒ c → × a → × b → = 12 a → - 12 α b → ⇒ c → × a &#