(i)[4]
In the case $k = 2$, calculate angle $AOB$.
(ii)[4]
Find the values of $k$ for which $\overrightarrow{AB}$ is a unit vector.
Mathematics 9709 · AS & A Level · Coordinate geometry
Coordinate geometry — practice question
The position vectors of points $A$ and $B$, measured from the origin $O$, are given by $\overrightarrow{OA} = \begin{pmatrix}1\\0\\2\end{pmatrix}$ and $\overrightarrow{OB} = \begin{pmatrix}k\\-k\\2k\end{pmatrix}$, where $k$ is a constant.