a slice
A "chord" in geometry is the line connecting two points on a circle. If you think if a pie slice, the chord is the outer crust.
A slice, a segment or a sector.----------------A segment is the area of a circle between the chord and the arc. A "sector" is what you are looking for. See the links below.
Concentric Circles?
We call it a circle.
It is a sector of the circle
a slice
A region of a circle called a pie slice is also called a sector. The sector is one of the main slices of a circle, the other is called a segment.
A segment? Or, possibly, an orange slice.
A sector is a part of a circle, like a slice of pie.
A slice (Pie) Octant
A cross section, I believe
sector
a slice
SLIVER
A circle.
It is a sector