MCQ
If $ a,b,c $ are three coplanar vectors, then $[a + b\,\,b + c\,\,c + a] = $
  • A
    $[a b c]$
  • B
    $2 [a b c]$
  • C
    $3 [a b c]$
  • $0$

Answer

Correct option: D.
$0$
d
(d) $[a + b\,\,b + c\,\,c + a]$$ = [a\,b\,c] + [a\,b\,a] + [a\,c\,c]$

$ + [a\,c\,a] + [b\,b\,c] + [b\,b\,a] + [b\,c\,c] + [b\,c\,a]$

$ = [a\,b\,c] + [b\,c\,a] = 2[a\,b\,c] = 0$, ($a,b,c $ are coplanar).

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