circle

Question 1

set of points in a plane that are all equidistant from a given point, called

Answer 1

center,

Question 2

Any segment
with endpoints at the center and a point on the circle

Answer 2

radius

Question 3

if r2= 0,

Answer 3

graph is a single point

Question 4

if r2< 0, then

Answer 4

there is no graph since r is imaginary