Taking the definition of line as Axiom , that is a Segment which when produced in both direction has no end, has negligible thickness, and Infinite length.
The three figures which can be precisely defined by using only undefined terms(Axiom or Postulate), are
1. Angle =Formed by intersection of two rays, as ray is a part of line.
2.Line Segment=Part of Line
3. Parallel lines =When two lines are placed in such a way that, the Perpendicular distance between them is always constant , we call it parallel lines.
