1.
polygon
A closed plane figure with three or more straight sides.
三角形も四角形も多角形の一種だ。
Both triangles and quadrilaterals are types of polygons.
正多角形は全ての辺と角が等しい。
A regular polygon has all sides and angles equal.
六角形は六つの辺を持つ多角形だ。
A hexagon is a polygon with six sides.
多角形 is the general mathematical term for any polygon. Composed of 多 (many) + 角 (angle/corner) + 形 (shape).
COMMON POLYGONS:
- 三角形: triangle (3 sides)
- 四角形: quadrilateral (4 sides)
- 五角形: pentagon (5 sides)
- 六角形: hexagon (6 sides)
- 八角形: octagon (8 sides)
RELATED TERMS:
- 正多角形: regular polygon (all sides and angles equal)
- 辺: side (of a polygon)
- 頂点: vertex
- 内角: interior angle
- 対角線: diagonal
PATTERN:
The suffix 〜角形 is productive: number + 角形 forms any polygon name.