In a triangle P Q R , let a → = Q R → , b → = R P → and c → = P Q → . If a → = 3 , b → = 4 and a → . c → − b → c → . a → − b → = a → a → + b → , then the value of a → × b → 2 is _______

Step-by-step solution

a → + b → + c → = 0 ∵ a → . c → − b → c → . a → − b → = a → a → + b → ⇒ − b → + c → ⋅ c → − b → − a → + b → ⋅ a → − b → = a → a → + b → ⇒ c → 2 − b → 2 a → 2 − b → 2 = 3 3 + 4 = 3 7 ⇒ c → 2 = 13 Now, a → + b → = − c → ⇒ a → + b &#85