<Dd> ((x, y) (x − c x) 2 + (y − c y) 2 + (x − a x) 2 + (y − a y) 2 = (c x − a x) 2 + (c y − a y) 2) (\ displaystyle \ ((x, y) (\ sqrt ((x-c_ (x)) ^ (2) + (y - c_ (y)) ^ (2))) + (\ sqrt ((x-a_ (x)) ^ (2) + (y - a_ (y)) ^ (2))) = (\ sqrt ((c_ (x) - a_ (x)) ^ (2) + (c_ (y) - a_ (y)) ^ (2))) \)). </Dd> <Ul> <Li> A line segment is a connected, non-empty set . </Li> <Li> If V is a topological vector space, then a closed line segment is a closed set in V. However, an open line segment is an open set in V if and only if V is one - dimensional . </Li> <Li> More generally than above, the concept of a line segment can be defined in an ordered geometry . </Li> <Li> A pair of line segments can be any one of the following: intersecting, parallel, skew, or none of these . The last possibility is a way that line segments differ from lines: if two nonparallel lines are in the same Euclidean plane they must cross each other, but that need not be true of segments . </Li> </Ul> <Li> A line segment is a connected, non-empty set . </Li> <Li> If V is a topological vector space, then a closed line segment is a closed set in V. However, an open line segment is an open set in V if and only if V is one - dimensional . </Li>

F then line segment is parallel to line segment