Final answer:
Without a visual or description of the stained-glass design, it's impossible to state the exact number of lines of symmetry in the stained-glass panel. Symmetry depends on the specific design.
Step-by-step explanation:
To determine the number of lines of symmetry in a stained-glass panel, one would need to look at the specific design of the panel. A design has a line of symmetry if one can fold it along that line and have both halves match each other exactly. The number of lines of symmetry can be one (as in case of a rectangle), two (as in the case of a rectangle who has also a line of symmetry through its shorter centreline), three (like in an equilateral triangle), or more. Without a visual or description of the stained-glass design in the question, it is impossible to provide a definitive answer to how many lines of symmetry the specified stained-glass panel has.