Any polygon with four or more sides can have a pair of parallel sides. It is also possible to to have non-polygonal shapes - eg a cigar-shape - that has parallel sides.
It can have anywhere between 0 and 12 pairs of parallel sides.
a rhombusNotice that if all 4 sides are equal, then they must be parallel.
any rhombus
A triangle as no other 2d shape can have 3 sides.
Any polygon with four or more sides can have a pair of parallel sides. It is also possible to to have non-polygonal shapes - eg a cigar-shape - that has parallel sides.
It can have anywhere between 0 and 12 pairs of parallel sides.
a rhombusNotice that if all 4 sides are equal, then they must be parallel.
rhombus
trapezoid
A square, a rectangle or a rhombus !
a trapizoid is the 2d shape for that
any rhombus
A triangle as no other 2d shape can have 3 sides.
Any polygon with four or more sides can have parallel lines. So also can some irregular shapes.
A 2D shape with 9 sides is called a Nonagon.
The shape of 2D is a flat surface.