Complex sentence: In spherical geometry, a finite henagon can be drawn by placing a single vertex anywhere on a great circle this forms a "henagonal dihedron", Schläfli symbol, with two hemispherical henagonal faces which share one 360 degree edge and one vertex.
Split into simpler sentences: In spherical geometry, a finite henagon can be drawn by placing a single vertex anywhere on a great circle. A "henagonal dihedron", defined by with Schläfli symbol, with two henagonal faces which share one edge and one vertex.