Assertion (A): The vectors a and (-2 a ), where a ≠ 0 are collinear vectors. Reason (R): a ·(-2 a )=0.

Assertion (A) : The vectors $\displaystyle \overrightarrow{\mathrm{a}}$ and $\displaystyle (-2 \overrightarrow{\mathrm{a}})$, where $\displaystyle \overrightarrow{\mathrm{a}} \neq \overrightarrow{0}$ are collinear vectors. Reason (R) : $\displaystyle \overrightarrow{\mathrm{a}} \cdot(-2 \overrightarrow{\mathrm{a}})=0$.