parallelogram
A nonagon is a nine-sided polygon. In a nonagon, there are four pairs of parallel lines. This is because the nonagon can be divided into three sets of parallel lines, each containing three parallel lines. Each set of parallel lines consists of three pairs of parallel lines.
Parallelogram
A square is a regular polygon with two sets of parallel sides. A parallelogram is an irregular polygon with one set of parallel sides. A rhombus is an irregular polygon with two sets of parallel sides. A rectangle is an irregular polygon with two sets of parallel sides. *Note - a regular polygon is a shape in which all sides are equal in length and all angles are equal in measurement.
A regular decagon would have five sets or parallel lines.
You can construct any polygon with more than 4 sides such that two sides are parallel. A quadrilateral in which two lines are parallel is called a trapezoid.
parallelogram
Since you described it as 2 sets of parallel sides, I'll assume you meant a 4 sided polygon(quadrilateral). This special case is called a rhombus.
When it has two sets of parallel lines
When it has two sets of parallel lines
A parallelogram.
Parallelogram
there are 2 sets of parallel lines in a square
A square has four sets of parallel lines.
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 :)
When it has two sets of parallel lines
General term for a polygon with 4 sides is a quadrilateral. A parallelogram is the special case with two pairs of parallel sides.