Relative to an origin O, the position vectors of points A and B are 3i + 4j - k and 5i - 2j - 3k respectively.

(i) Use a scalar product to find angle BOA.

The point C is the mid-point of AB. The point D is such that \(\overrightarrow{OD} = 2\overrightarrow{OB}\).

(ii) Find \(\overrightarrow{DC}\).