Which of these is the best definition of a circle? A. The set of all points in a plane that are equidistant from a single point
and a line B. The set of all points in a plane for which the sum of the distances to two fixed points equals a certain constant 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
The right answer is C. The set of all points in a plane that are a certain distance from a single point
The certain distance is called the <em>radius</em> and the single point is called the <em>center. </em>In this way, all points are a certain or, in other words, the same distance from the center. So, for the Standard Form of the Equation of a Circle we have that: