## Circles

### Glossary

**Unit circle**: Circle with centre at \((0, 0)\) and a radius of 1
**Circle**: Set of all points a given distance from a point
**Radius**: Any line segment that connects a point on the circle to the centre
**Tangent line**: A line that intersects only a single point on the circle
**Seacant line**: A line that intersects two points on a circle
**Chord**: :A line segment between two points on a circle
**Diameter**: A chord that goes through the centre of a circle. Length of a diameter is equal to \(radius * 2\)
**Arc**: Connecting two points on a circle.
**Minor arc**: The shortest way around the circle connecting two points
**Major arc**: The longest way around the circle connecting two points

**Circumference**: Length of the circle from a point all the way around back to itself; or the length of a major arc between one point and itself
**\(\pi\) / Pi**: A constant of approx 3.14. It is the ratio between the circumference and the diameter of a circle
**Circumference & \(\pi\)**: The circumference of a circle is \(\pi2r\)
\(\pi = \frac{circumference}{diameter}\), \(circum. = \pi diameter\), \(c = \pi2r\)