The continuous curved line that forms the boundary of a circle, defining its outer edge and distinct from the circle itself in geometric terms.
The ratio of the length of a circle's circumference to its diameter, a constant value represented by the symbol π (pi), approximately equal to 3.1416, which is fundamental to the study of circles.
The line that represents the distance around a circle, which is conceptually related to the circle but is not commonly referenced in the same terms as the circle itself.
A mathematical constant that represents the ratio of the circumference of a circle to its diameter, remaining constant regardless of the circle's size, typically denoted by the symbol π.
A transcendent number that is approximately equal to 3.141592, essential in geometry and trigonometry for computations involving circles.