A circle is one of the most fundamental shapes in geometry. It is defined as the set of all points that are exactly the same distance from a fixed center point. This constant distance is called the radius. Let's see how a circle is formed by plotting points at equal distances from the center.
A circle has several important components and measurements. The radius is the distance from the center to any point on the circle. The diameter is twice the radius and passes through the center. The circumference is the distance around the circle, calculated as 2 pi r. The area inside the circle is pi r squared. Pi is approximately 3.14159.
Circles have several fundamental properties. All radii of a circle are equal in length. The diameter is the longest possible chord. A tangent line is always perpendicular to the radius at the point of contact. Central angles correspond to equal arcs. Chords connect any two points on the circle.