Pat-piên-hìn
外觀
![](http://178.128.105.246/host-http-upload.wikimedia.org/wikipedia/commons/thumb/e/e5/Regular_polygon_8_annotated.svg/390px-Regular_polygon_8_annotated.svg.png)
Pat-piên-hìn (Yîn-ngî: Octagon) he chṳ́ yit-ke yù pat-thiàu siông-thùng chhòng-thu ke piên lâu pat-ke siông-thùng thai-séu ke kok kèu-sṳ̀n ke Chang Tô-piên-hìn. Chhai yit-ke chang pat piên hìn lî, mî yit-ke kok ke thai-séu tû-he 3π/4rad, chit tén-yî 135thu. Kì ke sṳ̂ lòi fû li fù-ho he {8}. Tui yî yit-ke piên-chhòng he a ke chang pat piên hìn, kì ke mien-chit yì hâ:
Chang Liuk-piên-hìn chhak-kûi chok-thù
[phiên-siá | kói ngièn-sṳ́-mâ]![Chang Pat-piên-hìn.](http://178.128.105.246/host-http-upload.wikimedia.org/wikipedia/commons/thumb/f/f7/Regular_Octagon_Inscribed_in_a_Circle.gif/450px-Regular_Octagon_Inscribed_in_a_Circle.gif)