They do not have any specific name.
They are parallel lines
A pair of parallel lines, an ellipse or a circle.
no
There cannot be parallel lines in any [plane] triangles.
Maybe
A cylinder includes an infinite number of parallel lines. Every line in the curved surface is parallel to every other one and perpendicular to the two ends. . "A cylinder 2" is meaningless. You would have to look at the homework you're trying to get the answer for to see what cylinder 2 means.
Infinitely many.
Yes a trapezoid has parallel lines
yes it has 2 parallel lines
A cone does not have any parallel lines
The two circles at the top and bottom of the cylinder are parallel faces.
An octagon need not have any parallel sides. But it can have any number from 2 to 8 lines that are parallel - in pairs, triplets or quartets.
A dodecahedron need not have any parallel lines.
They do not have any specific name.
The parallel sides of a polygon are sides that are segments of parallel lines. A polygon need not have any parallel lines. A triangle, for example, is a polygon that cannot have parallel lines.
parallel lines are those line which does not have any intersecting point.