Question

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

Explanation:

• A line segment is defined using the undefined term line (a part of a line with two endpoints).
• Perpendicular lines are defined using the undefined term line (two lines that intersect at a right angle).
• Parallel lines are defined using the undefined terms line and plane (two lines in the same plane that do not intersect).
• A ray is defined using the undefined term line (a part of a line with one endpoint and extending infinitely in one direction).

So, the undefined terms line and plane are needed to precisely define parallel lines.

Answer:

C. parallel lines