50
* * * * *
Or a number smaller than 50 - including zero.
Infinitely many.
A 15 sided polygon has 15 lines of symmetry;) Thanks for asking:)
There are three diagonal lines in a six sided Polygon(Hexagon)
65
None.
5 pairs of parallel sides.
Well a nonagon is a nine sided polygon. If you make the lines or sides parallel, then you will have a parallel figure. Or some parallel lines on a figure (polygon). If you choose to make your polygon (nonagon) have a pair of congruent sides, then your polygon will have some congruent sides. Therefore it really matters what your shape looks like. For example, a quadrilateral can be a square or a kite (or many others but I'm just using these) a kite might have no parallel lines and a square may have 2 sets of parallel lines. Do you get it? Does that answer your question? FYI: A nonagon is also known as a enneagon :)
A regular 24 sided polygon has 24 lines of symmetry.
36
A regular Undegon (11 sided polygon) has 11 lines of symmetry. It also has an order of rotation symmetry of 11.
24
14