tri·sect /ˈtraɪˌsɛkt, traɪˈ/
  (vt.)分成三部分,分成三截,三等分
  Tri·sect v. t. [imp. & p. p. Trisected; p. pr. & vb. n. Trisecting.]
  1. To cut or divide into three parts.
  2. Geom. To cut or divide into three equal parts.
  ◄ ►
  trisect
       v : cut in three; "trisect a line"