As in Euclidean geometry, we have segments and rays as well as lines: a segment (green in the sketch) is that part of a line between two points (its endpoints), while a ray (blue) is that part of a line between a point (its initial point) and an edgepoint. There are Segment and Ray tools in the Toolbox to construct these.

Once we have segments, we can talk about triangles, quadrilaterals and other polygons: the definitions are direct analogues to their Euclidean counterparts (a triangle, for example, has three points as vertices and the segments they determine as sides). But a word of caution: specific types of polygons may not exist in the Poincaré universe: without parallelism, for example, what is a parallelogram?