All regular polygons with an even number of sides. Irregular polygons with an odd number of sides can have parallel sides. There are also non polygonal shapes that can have parallel sides.
Infinitely many. Every regular polygon with 2n sides has n pairs of parallel sides. Then there are irregular polygons which can have parallel sides. And there are also irregular shapes which have parallel sides.
A shape with four or more sides can have two parallel sides.
There are no parallel sides on a nonagon (nine-sided figure)... Regular shapes with an odd-number of sides have no parallel sides.
It is impossible. You must have at least two sides which are parallel to one another.
Most irregular shapes don't have parallel sides By: SupeRMAn
no some shapes like the rhombus have 4 sides making it a quadrilateral but 2 of its sides are not parallel