Question

applying undefined terms in definitions
the undefined terms line and plane are needed to precisely define which mathematical term?
line segment
perpendicular lines
parallel lines
ray

Explanation:

• Line segment: Defined using the undefined term line (a line segment is a part of a line between two endpoints).
• Perpendicular lines: Defined using the undefined term line (two lines are perpendicular if they intersect at a right - angle).
• Parallel lines: Defined using the undefined terms line and plane (parallel lines are lines in a plane that do not intersect).
• Ray: Defined using the undefined term line (a ray is a part of a line that starts at a point and extends infinitely in one direction).

Answer:

parallel lines