Question

$\vec A$ is a vector quantity such that
$|\vec A|$ = non-zero constant.
Which of the following expression is true for $\vec A$?

• A. $\vec A.\vec A=0$
• B. $\vec A \times \vec A<0$
• C. $\vec A \times\vec A=0$
• D. $\vec A \times\vec A>0$

Answer 1

Answer: (C)

$\vec A \times\vec A=0$

Answer 2

$\vec A \times \vec A = A \times A \times sin\ 0°$
$= 0$

So, the correct option is (C): $\vec A \times\vec A=0$