define "sector" in a mathematical sense in simple terms

In mathematics, a sector refers to a region of a circle enclosed by two radii and the corresponding arc between them. It is like a slice or a piece of a pizza. The two radii form the boundaries of the sector, and the arc gives its curved shape. The angle between the radii determines the size of the sector.

use simpler terms

In math, a sector is like a chunk of a circle. It is formed by drawing two lines from the center of the circle to its edge and then connecting those lines with a curved line. It's like taking a slice of pie from a round pie. The size of the sector is determined by the angle between the two lines.