the shape has 1 side of symmetry
It is not possible to have 1 parallel side since it must be parallel to another side. A four sided shape with 1 PAIR of parallel sides is a trapezium (or trapezoid).
Any curved shape such as a circle, an ellipse, an oval, a wriggly line - as long as it does not have any corners.
Cone....
Extend any straight side of a shape. The angle made by that side with the adjacent side of the shape is an exterior angle. Its value is 180 degrees less the interior angle.
a circle
A semicircle.
A two dimentional shape with 1 side and 1 vertex.
A vertical line
A sphere
a quadrilateral
Irregular shape is the term given to an object which has 1 flat side, 1 curved side, no corners but has curved edges.
the shape has 1 side of symmetry
A semicircle is one shape fitting this description.
A line. Or a circle
A cylinder.
A "Math Trapazoid" is a shape that has 4 sides. There is 1 long side on the bottom, 1 medium sized side on the top, and 2 equal slanted sides on the sides of the shape.