Circles are round two-dimensional figures. Its main characteristic is that each point on the circumference is located at a constant distance from a fixed point. The constant distance is called the radius and the fixed point is called the center of the circumference. Some of the most important elements of the circle are the radius, the center, the diameter, the tangent, the secant, the chord, the arc, and others.

Here, we will look at these and other elements of a circle in more detail. We will use diagrams to illustrate these concepts.

GEOMETRY
elements of a circle

Relevant for

Learning about the fundamental elements of a circle.

See elements

GEOMETRY
elements of a circle

Relevant for

Learning about the fundamental elements of a circle.

See elements

Fundamental elements of a circle

The main elements of a circle are:

  • Center
  • Radius
  • Arc
  • Chord
  • Diameter
  • Tangent
  • Secant
elements of a circle

Center

The center of a circle is the point that is located on the inside and is equidistant from any point on the circle.

Radius

The radius is the distance or line segment that extends from the center to any point on the circumference.

Arc

The arc is a portion of the circumference that is bounded by two points on the circumference.

Chord

The chord is a line segment that joins a pair of points on the circumference.

Diameter

The diameter is considered as a chord that passes through the center of the circumference. The diameter is exactly twice the radius.

Tangent

The tangent is a straight line that touches the circumference at a single point. The point where the tangent touches the circumference is known as the point of tangency.

Secant

The secant is a straight line that touches the circumference at two different points.


Other elements of a circle

The following are other important elements of a circumference:

  • Semicircumference
  • Central angle
  • Inscribed angle

Semicircumference

The semi circumference is limited by the ends of the diameter. This means that it is an arc equal to half the circumference.

diagram of semicircumference

Central angle

The central angle of the circle is any angle, which has sides that are equal to the radius of the circle.

diagram of central angle in a circle

Inscribed angle

The inscribed angle of the circumference is an angle that has the vertex on the circumference and that has sides that are chords of the circumference. This angle is inscribed in the arc that contains the vertex.

diagram of an inscribed angle

See also

Interested in learning more about circles and circumferences? Take a look at these pages:

Learn mathematics with our additional resources in different topics

LEARN MORE