4 Two points \(A\) and \(B\) have coordinates \(( - 1,1 )\) and \(( 3,4 )\) respectively. The line \(B C\) is perpendicular to \(A B\) and intersects the \(x\)-axis at \(C\).
- Find the equation of \(B C\) and the \(x\)-coordinate of \(C\).
- Find the distance \(A C\), giving your answer correct to 3 decimal places.