parallelogram or a rhombus * * * * * Incorrect. A parallelogram or rhombus have two pairs (ie 4) of parallel sides, and that is not the same as exactly two parallel sides. The correct answer is any polygon with with four or more sides of which only two are parallel. The only one of these with a specific name is a quadrilateral and the name is a trapezium.
A polygon (joke). I don't think there is a name for that, though.
There is no particular name. It need not be a regular polygon - for example, consider a stretched hexagon.
There is no generic name. Any polygon with 4 or more sides can have 2 parallel sides. There are also non-polygonal shapes that can have parallel sides: for example, a circle that is stretched out into a cigar shape can have two parallel sides.
Paralellagram * * * * * No. A parallelogram (check spelling) has two PAIRS of parallel sides which is not the same as exactly two parallel sides. The correct answer is any polygon with with four or more sides of which only two are parallel. The only one of these with a specific name is a quadrilateral and the name is a trapezium.
The name of a polygon with 15 sides is a pentadecagon
A pentagon is the polygon with 5 sides.
A polygon with seven sides is a heptagon.
There is no formula for how many sides there are in a polygon; the name of the polygon shows how many sides it has.
For a 4-sided polygon (a quadrilateral), the shape is a trapezoid (trapezium in the UK).*The question was copied in and omitted the "4 sided" restriction. There are innumerable irregular polygons that have a single pair of parallel sides, those that have 5 or more sides.