We are given the radius of a circle.
[tex]r=338\: cm[/tex]The diameter is 2 times the radius of a circle.
So, the diameter of this circle becomes
[tex]\begin{gathered} d=2\times r \\ d=2\times338 \\ d=676\: cm \end{gathered}[/tex]Therefore, the diameter of the given circle is 676 cm.