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1)

If a, b and c are unit vectors  such that  a+b+c=0  and (a,b)=π3, then

|a×b|+|b×c|+|c×a|=


A) 32

B) 0

C) 332

D) 3

Answer:

Option C

Explanation:

 We have,

a,b,c are unit vector

   |a|=|b|=|c|=1  and a+b+c=0 , angle between a and b is π3

Now,      a+b+c=0

    a×(a+b+c)=0

  a×a+a×b+a×c=0

      a×b=c×a

   |a×b|=|c×a|

Similarly , |a×b|=|c×a|

  |a×b|+|b×c|+|c×a|

                                      =3|a×b|

                                    =3|a||b|sin(a,b)

                                      =3×1×1×sinπ3=332