8 Relative to an origin \(O\), the position vectors of points \(A\) and \(B\) are given by
$$\overrightarrow { O A } = \left( \begin{array} { c }
3 p
4
p ^ { 2 }
\end{array} \right) \quad \text { and } \quad \overrightarrow { O B } = \left( \begin{array} { c }
- p
- 1
p ^ { 2 }
\end{array} \right)$$
- Find the values of \(p\) for which angle \(A O B\) is \(90 ^ { \circ }\).
- For the case where \(p = 3\), find the unit vector in the direction of \(\overrightarrow { B A }\).