A heptahedron is a closed 3-d shape with 7 polygonal faces. There are 34 topologically different convex heptahedra and, since none of these are regular, the term is ambiguous. There can be:
as well as many other combinations.
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A pentagonal heptahedron is a heptahedron comprising two pentagons which are joined to one another by five quadrilaterals. There is no requirement for the pentagons to be congruent nor for them to be parallel to one another.
A square has 2 pairs of opposite parallel lines.
There cannot be parallel lines in any [plane] triangles.
there are 2 sets of parallel lines in a square
A diamond has two pairs of parallel lines.