That is because an octagon is singular and polygons is plural. An octagon is a polygon, and octagons are polygons but a octagon cannot be a polygons.
square and octagon
Triangle, rectangle, pentagon, hexagon, octagon. Though, there are much more names of polygons.
These are all names of polygons.
An 8 sided octagon belongs to the family of polygons
A square, pentagon, decagon, octagon are always regular polygons.
Octagon.
If the octagon is a regular octagon (all eight sides and all eight angles are equal), then it is a regular polygon. If it is not a regular octagon (i.e. if it is an irregular octagon) then is it an irregular polygon.
Octagon
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.
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.
These are all names of polygons.
No because an octagon has 8 sides whereas a triangle has only 3 sides but they are both polygons.
An 8 sided octagon belongs to the family of polygons
No, an octagon has eight sides while a hexagon has only six. However they're both types of polygons.