Circle and circumference

A circle is a flat surface delimited by a series of points in the shape of a curve.

A circumference is a continuous curved line.

The difference between circle and circumference is that the circle is all the area that is contained within the circumference, while the circumference is the outer edge of the circle.

	Circle	Circumference
Definition	Flat surface bounded by a circumference.	Curved line that delimits and contains a circle.
Parts	Bow. String. Radio. Diameter. Center.	Bow. String. Radio. Diameter. Center. Tangent line. Secant line.
Measuring length	Area	Perimeter
Formula	A = π. r2	P = 2r.π

What is a circle?

It is a surface composed of a series of exterior points, called the circumference, and of all the points that are inside..

Being a flat surface, every circle has an area.

The formula to calculate the area is:

A = π. r2

The area of ​​a circle is equal to Pi (3.1416) multiplied by the radius squared.

Parts of a circle

• Bow: is a portion of the circle formed by a curve that joins two points.
• String: is the distance between the two points of an arc.
• Radio: is the distance from the center of the circle to any of the points on the circle. It is half the distance of the diameter.
• Diameter: is the distance between two points that pass through the center of the circle. That is, twice the radius distance
• Center: is the point at which all other equidistant points of the circle converge.

What is a circumference?

A circle is a continuous, flat and closed curved line, composed of a series of points that are equidistant from a common center.

Since the circumference is a line and is not a flat surface, it has no area, but it does have a perimeter.

The formula to calculate the perimeter is:

P = 2r.π

The perimeter is equal to the radius multiplied by 2 and this product in turn is multiplied by Pi (3.1416).

Parts of a circle

A circumference shares the elements of a circle (arc, chord, radius, diameter and center), but also has:

• Tangent line: it is a straight line that touches the circumference at a single point.
• Secant line: it is a straight line that cuts the circumference at two points.

See also Types of angles.