Geometry · Circles
Inscribed Angle
HSG-C.A.2
Definition
An angle with its vertex on the circle; it measures half its intercepted arc.
Examples
- An inscribed angle of 40 degrees corresponds to an intercepted arc of 80 degrees.
- If the intercepted arc is 100 degrees, the inscribed angle measures 50 degrees.
Key rule
An inscribed angle is always half the measure of its intercepted arc.
Memory hook
Vertex on the circle — angle is half its arc.