Nonagon – a polygon with 9 sides
NiNe of them
Nine of them sounds like nonagon so makes this easy to remember.
If none are gone (nonagon) then a cat has nine lives.
A regular nonagon has nine sides of equal length.
If you add up all the internal angles of a regular convex nonagon you will get 1260°.
A regular convex nonagon has an internal angle of 140° between each side.
This shape looks like a Y but as it has 9 sides, it’s a nonagon.
Irregular nonagons such as this one may not have a symmetrical shape but will still have nine sides.