Q.

Let a and b be two vectors such that |b|=1 and |b×a|=2. Then |(b×a)b|2 is equal to          [2024]

1 5  
2 1  
3 4  
4 3  

Ans.

(1)

Given, |b|=1 and |b×a|=2

Now, |(b×a)b|2=|b×a|22(b×a)·b+|b|2

=(2)2+12(0)=5.