Use the given sets to find $A \cup B$. \[ \begin{array}{c} A=\{1,2,3,4,5,6,7,8,9\} \\ B=\{3,5,7,9,11,13\} \end{array} \]

Step 1 ：Given sets are: \(A = \{1, 2, 3, 4, 5, 6, 7, 8, 9\}\) and \(B = \{3, 5, 7, 9, 11, 13\}\).

Step 2 ：The union of two sets is a set containing all the elements of both sets. It's a combination of all the unique elements from both sets.

Step 3 ：So, the union of sets A and B, \(A \cup B\), is \(\boxed{\{1, 2, 3, 4, 5, 6, 7, 8, 9, 11, 13\}}\).