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 9 sided nonagon normally has no perpendicular lines that meet at right angles
A nine sided nonagon has 27 diagonals
parallel
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.
Up to four.
In general, none, but there can be nine.
A triangle can have no parallel lines.