Angle Relationships in Circles

Central Angles
A central angles is an angle formed by two radii and vertex at the center of a circle.
Inscribed Angles
An inscribed angle is an angle formed by two intersecting chords or secants with its vertex "on" the circle.
Tangent & Chord Angles
An angle formed by an intersecting tangent and chord has its vertex "on" the circle.
Intersecting Chords/Secants
An angle formed by two intersecting chords or secants has its vertex inside the circle. Two sets of vertical angles are created.
Angles Outside the Circle
An angle formed by two secants, a secant and a tangent, or two tangents, has its vertex outside the circle if the lines intersect outside the circle.
– Zachary Parnell, M Braddock

Information: Angle Relationships in Circles