Line Intersections in a Plane
Theorem: Lines in a Plane
For every two distinct [[Straight Line|straight lines]] which lie in the same [[Planes|plane]] there are two possibilities:
- The lines intersect in a single [[Euclidean Geometry|point]].
- The lines do not intersect.
Proof
TODO
Definition: Parallel Lines
Two [[Straight Line|straight lines]] are parallel if they lie in the same [[Planes|plane]] but do not [[Line Intersections in a Plane|intersect]].