4. Line segment and ray are some of the examples of what concept?
a. defined terms
c. theorem
b. undefined terms
d. postulate
5. "A gentle torturer" is a specific example of what concept?
a. Theorem
c. Principle of Contradiction
b. Postulate
d. Axiom
6. What is the image shown in the right?
a. point
b. plane
d. ray
C. line
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