Question

The definition of a circle uses the undefined term _______.

Answer 1

Answer:

C. Plane  

Step-by-step explanation:

One definition of a circle is: "It is the set of all points in a plane that are at a given distance from a fixed point."

The undefined term is the word "plane."

You could define a plane as a flat surface with zero thickness and extends infinitely in all directions, but it isn't in the definition of a circle.

Euclid defined a plane as "a surface that lies evenly with the lines on it" before he defined a circle, so the meaning was understood.

A, B, and D are wrong. They aren't mentioned in the definition.