They are polygons
Triangle, octagon, and my favorite, dodecagon.
Regular polygons like an octagon have the same number of corners as they do sides, so an octagon would have 8.
square and octagon
Triangle, rectangle, pentagon, hexagon, octagon. Though, there are much more names of polygons.
Polygon means many sides. Octagon mean eight sides. Not all polygons are octagons, but all octagons are polygons. Examples of other polygons are triangles, squares, parallelograms, rhombuses, pentagons, hexagons, heptagons, decagons
These are all names of polygons.
square or octagon
A list of polygons would include the triangle, quadrilateral, pentagon, octagon, and the hexagon. Some additional polygons are the enneagon, the heptagon, the dodecagon, and the hexdecagon.
No because an octagon has 8 sides whereas a triangle has only 3 sides but they are both polygons.