A nine sided nonagon has 27 diagonals
parallel
A square has 2 pairs of opposite parallel lines.
asma
There cannot be parallel lines in any [plane] triangles.
In a regular nonagon no two sides are parallel.
up to four pairs is the answer
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 :)
On a quick estimate, I would think 18, 9 for each interior side and another 9 for each interior angle. * * * * * A nonagon has only 9 lines so the above answer is nonsense. With 9 lines you can have at most 4 pairs of parallel lines (and one not parallel to any). Or you could have a concave nonagon with 1 pair, 1 triplet and 1 quartet of parallel lines, or some other combination.
There are no parallel sides on a nonagon (nine-sided figure)... Regular shapes with an odd-number of sides have no parallel sides.
A nonagon can have none, or anything up to four pairs of parallel sides. You can even have two quartets of parallel sides in you allow concave nonagons.
A 9 sided nonagon normally has no perpendicular lines that meet at right angles
A nine sided nonagon has 27 diagonals
parallel
Up to four.
In general, none, but there can be nine.
A triangle can have no parallel lines.