"Tiong-soàⁿ (kí-hô-ha̍k)" pán-pún chi-kan bô-kāng--ê tē-hng

[[ImageFile:Triangle.Centroid.png|thumb|Saⁿ-kak-hêng ê tiong-soàⁿ kap [[chit-sim]]]]

[[Saⁿ-kak-hêng]] lāi-té, '''tiong-soàⁿ''' tō sī 1 ê [[toan-tiám]] kap i tùi-bīn hit ê piⁿ ê [[tiong-tiám]] liân--khí-lâi ê soàⁿ. I ē kā saⁿ-kak-hêng chhiat chò 2 tè, 2 tè ê [[bīn-chek]] pêⁿ toā. 3 tiâu tiong-soàⁿ ē tī saⁿ-kak-hêng ê [[chit-sim]] ([[chit-liōng tiōng-sim]]) sio kau-chhe. Chit-sim ē kā ta̍k tiâu tiong-soàⁿ chhiat chò 2:1 ê 2 koe̍h [[soàⁿ-koe̍h]].