Weld Edges into Faces(辺を面に溶解)

参照

Mode(モード):

Edit Mode(編集モード)

Menu(メニュー):

Face(面) ‣ Weld Edges into Faces(辺を面に溶解)

Splits the selected faces along any selected wire edges (edges not part of any faces) that share their vertices. The wire edges become part of the new faces.

Selecting a quad face and a wire edge.

Welding splits the quad into two triangles.

参考

Instead of creating edges and then running this operator, it may be easier to use Connect Vertex Path(頂点の経路を連結) or the Knife Topology Tool to split the faces directly.