Let a → and b → be two vectors such that | b → | = 1 and | b → × a → | = 2 Then | ( b → × a → ) - b → | 2 is…

Let a→ and b→ be two vectors such that |b→|=1 and |b→×a→|=2 Then |(b→×a→)-b→|2 is equal to
  1. 3
  2. 5
  3. 1
  4. 4

Solution

Given: b→=1, b→×a→=2

Now, solving b→×a→-b→2,

⇒b→×a→-b→2=b→×a→2+b→2-2b→×a→·b→

Now, we know that, b→×a→·b→=b→×a→·a→=0

⇒b→×a→-b→2=22+12-2×0

⇒b→×a→-b→2=5

Asked in: JEE Main 2024 (30 Jan Shift 2)

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