(a) Given that \(\mathbf p=2\mathbf i-5\mathbf j\) and \(\mathbf q=\mathbf i-3\mathbf j\), find the unit vector in the direction of \(3\mathbf p-4\mathbf q\).

(b) A river flows between parallel banks at a speed of \(1.25\text{ km h}^{-1}\). A boy standing at point \(A\) on one bank sends a toy boat across the river to his father standing directly opposite at point \(B\). The toy boat, which can travel at \(v\text{ km h}^{-1}\) in still water, crosses the river with resultant speed \(2.73\text{ km h}^{-1}\) along the line \(AB\).

(i) Calculate the value of \(v\).

(ii) The direction in which the boy points the boat makes an angle \(\theta\) with the line \(AB\). Find the value of \(\theta\).