The ornamental design for a panel with a polygonpattern, as shown and described.
FIG. 1 is a front view of a panel with a polygon pattern, shown used in a partition structure;
FIG. 2 is an enlarged front perspective view of the panel with a polygon pattern in FIG. 1;
FIG. 3 is an enlarged top plan view taken along line 3-3 of FIG. 5;
FIG. 4 is an enlarged left side elevation view taken along line 4-4 of FIG. 5;
FIG. 5 is an enlarged front elevation view;
FIG. 6 is an enlarged right side elevation view taken along line 6-6 of FIG. 5; and,
FIG. 7 is an enlarged bottom plan view taken along line 7-7 of FIG. 5.
The broken lines showing environment in the drawings are included for illustrative purposes only and form no part of the claimed design. The outer broken line boundaries in the figures depicting the boundaries of the claimed design indicate that a specific length, width, and thickness form no part of the claimed design and are for illustrative purposes only.