Geometry · Circles
Sector
HSG-C.B.5
Definition
A region of a circle bounded by two radii and their intercepted arc.
Examples
- A sector looks like a pie slice, bounded by two radii and the arc between them.
- A quarter-circle sector has a central angle of 90 degrees.
Key rule
A sector is bounded by two radii and the arc they cut off — a 'pie slice' of the circle.
Memory hook
A pie-slice piece of the circle.