noun
- a polygon with nine sides and nine angles
Usage: also called a nonagon; geometry
Examples
- The enneagon is one of the less common polygons studied in basic geometry.
- To find the sum of interior angles in an enneagon, use the formula (9 – 2) × 180°.
- An enneagon has nine equal sides if it is regular.
- The architect incorporated an enneagon shape into the building's floor plan.
- Students learned to construct an enneagon using a compass and straightedge.