A circle (circle) is a geometric figure on a plane, all points of which are equidistant from a given point (the center of the circle).
Circle area formula where R is the radius of the circle

A circle (circle) is a geometric figure on a plane, all points of which are equidistant from a given point (the center of the circle).
Circle area formula where d is the diameter of the circle

A circle (circle) is a geometric figure on a plane, all points of which are equidistant from a given point (the center of the circle).
Circle area formula where L is the circumference