If $|\overrightarrow A \times \overrightarrow B |\, = \,|\overrightarrow A \,.\,\overrightarrow B |,$ then angle between $\overrightarrow A $ and $\overrightarrow B $ will be …….. $^o$

If $\overrightarrow P .\overrightarrow Q = PQ,$ then angle between $\overrightarrow P $and $\overrightarrow Q $ is ……. $^o$

Explain the geometrical interpretation of scalar product of two vectors.

If $\vec A,\vec B$ and $\vec C$ are vectors having a unit magnitude. If $\vec A + \vec B + \vec C = \vec 0$ then $\vec A.\vec B + \vec B.\vec C + \vec C.\vec A$ will be 

Let $\vec{A}=2 \hat{i}-3 \hat{j}+4 \hat{k}$ and $\vec{B}=4 \hat{i}+j+2 \hat{k}$ then $|\vec{A} \times \vec{B}|$ is equal to ……………….