If $\vec A = 2\hat i + \hat j – \hat k,\,\vec B = \hat i + 2\hat j + 3\hat k$ and $\vec C = 6\hat i – 2j – 6\hat k$ then the angle between $(\vec A + \vec B)$ and $\vec C$ wil be ……. $^o$

The angle between vectors $(\overrightarrow {\rm{A}} \times \overrightarrow {\rm{B}} )$ and $(\overrightarrow {\rm{B}} \times \overrightarrow {\rm{A}} )$ is

If diagonals of a parallelogram are $\left( {5\hat i – 4\hat j + 3\hat k} \right)$ and $\left( {3\hat i + 2\hat j – \hat k} \right)$ then its area is

Write the necessary condition for the scalar product of two mutually perpendicular vectors.

${\vec  A }$, ${\vec  B }$ and ${\vec  C }$ are three non-collinear, non co-planar vectors. What can you say about directin of $\vec  A \, \times \,\left( {\vec  B \, \times \vec  {\,C} } \right)$ ?