A circle is a flat surface bounded by a series of curved points.
A circle 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 delimited by a circumference.  Curved line that delimits and contains a circle. 
Parties 


Measuring length  Area  Perimeter 
Formula  A = π. R2  P = 2r.π 
Index
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) times the radius squared.
Parts of a circle
 Arc : it is a portion of the circle formed by a curve that joins two points.
 Chord : is the distance between the two points of an arc.
 Radius : 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 where all the 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 circle 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 .