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JEE Main20205 Sep 2020Evening ShiftMathematicsVector AlgebraActual

Let the vectors a → , b → , c → be such that | a → | = 2 , | b → | = 4 and | c → | = 4 . If the projection of b → on a → is equal to the projection of c → on a → and b → is perpendicular to c → , then the value of | a → + b → - c → | is …

Correct answer

0

Step-by-step solution

b → . a → = c → . a → a → + b → - c → 2 = | a → | 2 + | b → | 2 + | c → | 2 + 2 a → · b → - b → · c → - a → · c → = 4 + 16 + 16 + 2 ( a → . b → - 0 - a → . b → ) = 36 ⇒ | a → + b → - c → | = 6

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