Learn the vocabulary and components of circles
A circle is the set of all points equidistant from a center point.
| Part | Definition |
|---|---|
| Center | The point in the middle, equidistant from all points on the circle |
| Radius | Distance from center to any point on the circle () |
| Diameter | Distance across the circle through the center () |
| Circumference | Distance around the circle () |
| Chord | Line segment connecting two points on the circle |
| Arc | Part of the circumference |
| Sector | "Pizza slice" - region between two radii |
| Tangent | Line that touches the circle at exactly one point |
| Secant | Line that crosses the circle at two points |
Pi (π) is the ratio of circumference to diameter for ANY circle:
Pi is an irrational number - its decimal never ends or repeats!
Common approximations:
| Measurement | Formula |
|---|---|
| Circumference | |
| Area | |
| Diameter | |
| Radius |