A polygon is inscribed in a circle if and only if every vertex of the polygon lies on the circle.
In a plane, a line that intersects a circle at exactly one point.
A line that intersects a circle in two points.
A segment that contains a chord of a circle.
A segment of a circle whose endpoints are on the circle.
Point of Tangency
The point of intersection of a line and a circle in exactly one point.
An angle intercepts an arc if and only if each of the following conditions holds: 1) the endpoints of the arc lie on the angle.
2) All points of the arc, except the endpoints, are in the interior of the angle.
3) Each side of the angle contains an endpoint of the arc.
External Secant Segment
The part of a secant segment that lies outside of the circle.