A particle shows distance - time curve as given in this figure. The maximum instaneous velocity of the particle is around the point

$$\overrightarrow A $$ and $$\overrightarrow B $$ are two vectors and $$\theta $$ is the angle between them, if $$\left| {\overrightarrow A \times \overrightarrow B } \right| = \sqrt 3 \left( {\overrightarrow A .\overrightarrow B } \right),$$ the value of $$\theta $$ is

A particle starting from the origin (0, 0) moves in a straight line in the (x, y) planes. Its coordinates at a later time are $$\left( {\sqrt 3 ,3} \right)$$. The path of the particle makes with the x-axes an angle of

The vectors $$\overrightarrow A $$ and $$\overrightarrow B $$ are such that $$\left| {\overrightarrow A + \overrightarrow B } \right| = \left| {\overrightarrow A - \overrightarrow B } \right|.$$ The angle between the two vectors is