Which of these is the best definition of an ellipse?
o
a. the set of all points in a plane for which the sum of the distances
to two fixed points equals a certain constant
o
b. the set of all points in a plane that are equidistant from a single
point and a line
o
c. the set of all points in a plane that are a certain distance from a
single point
d. the set of all points in a plane for which the difference between
the distances to two fixed points equals a certain constant