Let a → = i ^ - j ^ , b → = i ^ + j ^ + k ^ and c → be a vector such that a → × c → + b → = 0 → and a → . c → = 4 , then | c → | 2 is equal to:

Step-by-step solution

Let the angle between a → and c → is θ . ∴     cos ⁡ θ = a →   .   c → a →   c → = 4 2   c → Given, a → × c → + b → = 0 ⇒     a → × c → = b → ⇒     a → .   c → sin ⁡ θ = b → ⇒       a → 2 c → 2 sin 2 ⁡ θ = b → 2 ⇒     2 c → 2 1 - cos 2 &#8289