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Let a → , b → and c → be three unit vectors such that a → × b → × c → = 3 2 b → + c → . If b → is not parallel to c → , then the angle between a → and b → is

Options

  1. A2 π 3
  2. B5 π 6
  3. C3 π 4
  4. Dπ 2

Correct answer

B. 5 π 6

Step-by-step solution

Given, a → × ( b → × c →   ) = 3 2   ( b → + c →   )   ⇒ a → · c → b → - a → · b → c → = 3 2   b → + 3 2 c → On comparing, we get - a → · b → = 3 2 ⇒ a → · b → = - 3 2 ⇒ a → b → cos θ = - 3 2 Given a → , b → are unit vector, a → = b → = 1 From equation i cos θ = - 3 2 ⇒ cos θ = cos 5 &#9

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