the.com/nonagon
the nine-sided shape nobody can draw with just a compass and straightedge
means A polygon with nine sides and nine angles.
from A Latin-Greek hybrid that linguists tend to wince at: Latin 'nonus' (ninth) bolted onto the Greek '-gon' (angle, from 'gonia,' a corner or knee — yes, the same root that gave us the geometry of bent things). Purists prefer 'enneagon,' all-Greek from 'ennea' (nine), but 'nonagon' won the popularity contest anyway.
- impossible build
- Cannot be constructed with classical compass alone
- interior angle
- Each corner is exactly 140 degrees
- other name
- Also called an enneagon, from Greek
- sum of angles
- All nine angles total 1260 degrees
- stop sign cousin
- One more side than the octagon
for instance
regular nonagon — 9-sided polygon with equal sides and angles, interior angle of 140 degrees
us steel tower — pittsburgh skyscraper with 64 floors arranged in a nonagonal footprint, completed 1970