対角線(たいかくせん)

対角線(たいかくせん) is a line segment connecting two non-adjacent vertices (corners) of a polygon.

Writing

• 対(たい): opposite, facing
• 角(かく): angle, corner
• 線(せん): line

Mathematics

The number of diagonals in a polygon with n sides is n(n-3)/2. For example, a square has 2 diagonals, a hexagon has 9.

Common expressions

• 対角線(たいかくせん)を引(ひ)く: to draw a diagonal
• 対角線(たいかくせん)の長(なが)さ: length of a diagonal
• 対角線(たいかくせん)で分(わ)ける: to divide by a diagonal

Related words

• 斜線(しゃせん): diagonal/slanted line (general)
• 対角(たいかく): diagonal; opposite corners
• 頂点(ちょうてん): vertex