A line is parameterized by a parameter \( t \), so that the vector on the line at \( t = 0 \) is \( \begin{pmatrix} 2 \\ 1 \\ 3 \end{pmatrix} \), and the direction vector of the line is \( \begin{pmatrix} 1 \\ -2 \\ 4 \end{pmatrix} \). 

(a) Find the vector on the line at \( t = 5 \). 

(b) Determine the angle between the vector on the line at \( t = 0 \) and the vector on the line at \( t = 5 \). Let's think step by step and output the final answer within \boxed{}.
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