paralellogram
The question contradicts itself. A dodecagon need not have any perpendicular sides.
shape no pairs of perpendicular sides
Any polygon can have only 1 pair of perpendicular sides.
I suppose. All of a square's sides are perpendicular.
No but its diagonals are perpendicular
A right angle has one pair of perpendicular sides.
The first geometric shape that comes to mind with no perpendicular sides is a triangle.
Any shape, other than a triangle can have a pair of perpendicular sides.
Yes.
Yes, they can exist.
A right triangle.