Geometry · Circles
Central Angle
HSG-C.A.2
Definition
An angle whose vertex is the center of the circle; it equals its intercepted arc.
Examples
- A central angle of 80 degrees corresponds to an 80 degree arc.
- A central angle of 45 degrees cuts off a 45 degree arc.
Key rule
A central angle's measure always equals the measure of its intercepted arc.
Memory hook
Vertex at the center — angle equals its arc.