A straight line perhaps
A triangle perhaps which has only 3 sides
[object Object]
I'm going to take a guess. A 2-D object must have at least three sides (a triangle) A 3-D object must have at least four sides (a triangular pyramid) I'm going to guess that a 4-D object must have at least 5 sides, if the pattern holds...
A quadrilateral is a geometrical shape that has 4 sides
a triangle
A geometrical figure with ten sides.
7
it means the object has at least 3 sides, but there are usually more.
A mirror image of an object is said to have a line of symmetry
PentagonsHexagonsOctagonsDecagons
its a nonagol
A geometrical shape with four equal sides.