A circle is the set of all points in a plane that have the same distance from the center.

A circle c can be defined as follows:

from three points A, B, C. The input is a list of three points.

from the two endpoints of a diameter of the circle c. The input is a list of two points.

from the center of c and its radius. The input is a list of two elements where the first element is a point, the second element is a number.

from its internal representation eqn. The input is an equation or a polynomial. If the optional argument n is not given:

if the two environment variables _EnvHorizontalName and _EnvVerticalName are assigned two names, these two names will be used as the names of the horizontal-axis and vertical-axis respectively.

if not, Maple will prompt for input of the names of the axes.

To access the information relating to a circle c, use the following function calls:

The command with(geometry,circle) allows the use of the abbreviated form of this command.